Episode 186 - Is your baby too big or too small?

January 18, 2026

Have you been told that your baby is too big or too small during your pregnancy? Do they want to induce you or give you a caesarean because your baby is too big or maybe it was too small? Are pregnant and have been told that your baby is too big or too small?

In this episode Mel shared her Guide to giving birth without pain medication, you can get it here.

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Episode Transcript

Episode 186 - Is your baby too big or too small?

[0:00] Welcome to the Great Birth Rebellion podcast. I'm your host,

[0:03] Dr. Melanie Jackson. I'm a clinical and research midwife with my PhD. And each episode, I cast a critical eye over current maternity care practice by grappling with research and historical knowledge to help you get the best out of your pregnancy, birth, and postpartum journey.

[0:24] Welcome to today's episode of the Great Birth Rebellion podcast. I'm your host, Dr. Melanie Jackson. I've been a midwife and private midwife for 18 years, and today I'm talking

[0:36] about the research on big babies and small babies during pregnancy. Now, with the increasing use of growth scans during pregnancy, more and more women are being given the diagnosis that their babies are either too big or too small and interventions are happening as a result, including increase in inductions.

[0:57] So today I want to look at the research on how the size of the baby is determined during pregnancy and if these methods are accurate enough to use for clinical decisions. So this episode is for you today. If you're being told by your care provider that your baby is either too big or too small, this episode gives you some information to consider as you make decisions going forward. But before we get into that, in order to keep this podcast free to you, the listener, we have a generous sponsor, Poppy Child from Pop That Mama, and she has just delivered something incredible. She taught a pain management for labor masterclass live in New York City, and the full replay is available now to watch and it's completely free. This session is all about how to cope with the intensity of labor and how to work with the sensations instead of fighting them. It's packed with real tools that you can use during birth and it's a must watch with your birth partner so that you both know how to respond to the reality of labor. It's not just a theory.

[2:03] The live event has now passed, but you can watch the full replay right away through the link in the show notes. It's an opportunity to learn everything that was taught live in New York, and you can only get access to it now if you sign up to watch the replay. So tap the link in the show notes and get watching.

[2:22] Okay, so let's get into it. First, I'll start by going over the definition of what is considered a small baby, and then we'll talk about what's considered a big baby and I'll explain the classifications to get us started. So what's a small baby? If your midwife or your doctor is saying or the ultrasound scan is saying hey your baby is on the small side. So once they're born small babies are considered to be anything below 2.5 kilos at birth and when I was a baby midwife an early midwife over 4.5 kilos was considered to be a big baby at birth. But now a lot of the research is saying that it's more realistic for four kilos to be considered a big baby. So if you have a baby that's suspected to be over four kilos at full term, this is described as macrosomia, macrosomic babies.

[3:19] Now, the Australian College of Midwives, which is one of the documents that guides our clinical practice here in Australia, and also a lot of research is now classifying babies who are suspected to be over four kilos as macrosomic. And certainly in the new 2025 ACM guidelines, they're telling midwives that if you suspect that a baby is over four kilos, that is a reason to refer on to a medical practitioner. It's a category C, which means, yeah, refer. No longer, it's just not a consultation process. I'm not sure I agree with that, but anyway, that's what it is here in Australia.

[3:57] So a big baby in the 19th centile, so this is how your ultrasound might describe it. They will give your baby a centile or a percentile. And a big baby on ultrasound is considered to be over the 90th centile. So that means that your baby is suspected to be bigger than 90% of babies. And that's considered large for gestational age. That's another word that people might use to describe your baby or macrosomia. And if your baby is small for gestational age, the ultrasound report will tell you that your baby is below the 10th centile, meaning that 90% of babies are bigger than yours at that particular gestational age. So these centiles can be used as a yardstick, a sort of a measuring stick at any time through pregnancy. And they might explain to you that your baby is above the 90th centile or below the 10th centile, representing either macrosomia or a small for gestational age baby.

[5:03] And then at the time of birth or at full term, below 2.5 kilos is considered small for gestational age and a baby over four kilos is large for gestational age. I'm not saying that any of this is right. I'm just telling you what the general medical definitions of these things are. This is the type of terminology that you'll hear from your clinicians and your care providers. And although there are small or big babies compared to the other babies in the world, there's also another classification to be aware of. And a small or large baby might not necessarily be pathological, and we'll have that discussion through this episode, but this particular thing is unusual and pathological. So this is to do with unusual growth and proportions of the baby. So big babies and small babies are the ones that are big or small all over. So proportionately big and small. However, with particularly small babies, they might be described as having intrauterine

[6:09] growth restriction, IUGR. And that's different to a baby that's just small for gestational age. So intrauterine growth restriction is a small baby, but all of the proportions of the baby's body are out. So the growth is different for the head, for the legs, for the abdomen.

[6:29] And so you might see things like a big head but a small body. Whereas with small babies, with small for gestational age babies, they're small all over and in proportion. All their measurements are approximately the same centaur. But with growth-restricted babies, their heads often grow disproportionately to their body. This indicates that there's actually an issue and the woman's body, your body, is trying to spare the baby's most important parts, the brain, and that's where the energy and the growth is going and it's at the expense of the baby's body and the rest of their proportions.

[7:08] And this is intrauterine growth restriction. This is pathological and points to an issue with the baby or the placenta or something with the mum. So this is something definitely to pursue additional medical help for, of course.

[7:24] But the question is, how do we determine the size of the baby before it's born? There's those three possibilities, large for gestational age, small for gestational age and intrauterine growth restriction. But how can we know and diagnose those things? And the truth of it is, is that we don't actually have an exact science or good enough skills or technology to accurately measure the weight of your baby before it's born. There are some measurements that can be done, which is what's used to determine the intrauterine growth restriction. But in terms of determining the weight and the centile of your baby. Is it below the 10th centile? Is it above the 19th centile? The technology we currently have is not considered accurate enough to give you the proper and right weight of your baby. There are some ways that we can take an educated guess though. So let's look at those possibilities. We'll look at how do we take an educated guess at the size and weight of your baby.

[8:28] From a midwifery perspective, so I'm a midwife, have been for 18 years, and we can do what's called a symphysis pubis measurement for, or we call it fundal height, checking fundal height. And basically we put our hands on your body and we feel above your belly button or around your belly button for the top of your uterus. It's called the fundus, the top of your uterus. And And that includes the size of the baby, the amniotic fluid, the placenta, the uterus. And we try and feel at what point do we get to the top of your uterus when we're feeling your belly with our hands. And we measure with a tape measure. From the top of your uterus, your fundus, and we measure all the way down to your pubic bone or the other way around. Depending on your technique, you might measure from the pubic bone up to the fundus. The important thing is to stay consistent with however you do it. Do it the same every single time. That's how you're going to get the most accurate measurement. But checking fundal height is a routine part of midwifery care. It's not something we leave out or something that we only do sometimes. The value of a fundal height is that it's done each time with the same technique and then you can more likely rely on its accuracy.

[9:47] We generally start measuring your fundus from around 24 weeks or the fundal height. But the midwife who trained me, she actually taught me how to measure with my fingers. Assuming your fingers are approximately a centimeter wide, this is what it relies on. But instead of measuring with a measuring tape, I mean, you run out of fingers at 28, at week 28. But at 16 weeks, if you were to try and feel your own fundus.

[10:15] So you'd be lying down and then you kind of start to feel a little ledge tennis ball type size at 16 weeks your fundus is around four fingers below your belly button at 20 weeks your uterus can be felt at the height of your belly button so you know for midwives out there listening as a rudimentary measurement instead of having to get the tape measure out you can find the fundus at 16 weeks, about four fingers below the umbilicus, the belly button, and 20 weeks at the umbi, at the belly button, and 24 weeks, it's four fingers above the belly button, which would be considered 24 centimeters. And that correlates with the number of weeks that you're pregnant. And that's what we do for fundal height. Approximately each week of pregnancy equals an increase of one centimeter growth in your fundus. This is not linear. It doesn't go one centimeter every week, of course. Sometimes your baby will have a growth spurt or a little bit of a rest period. That shouldn't last too long, but approximately one centimeter per week of gestation.

[11:20] And then when you get to 28 weeks, you're eight centimeters above your belly button. By that time, you've run out of fingers and we start to use a flexible measuring tape.

[11:31] So that's how midwives do it. That's how we look at the approximate size and growth of your baby. And the use of fundal height measurement is about determining if there has been growth. And we can work out if the growth is on track or has it suddenly stopped or has it suddenly accelerated. Now, this is how midwives do it. And also, there are some really skilled midwives who are used to putting their hands on women's bellies, and they can get a feel for the size of the baby too. You know, my colleagues and I often talk about, oh, it doesn't feel like a big baby, or it doesn't feel like a small baby. Feels like a normal baby, normal-sized baby.

[12:08] And this is just a matter of mastering a skill. Not all midwives have this ability because I do feel that the hands-on part of midwifery is slowly being lost. And also midwives are often working under a lot of time pressure and they're not able to fully connect and feel and be present with an abdominal check of a baby all the time. And also, often our workplaces don't really accept that midwives have this subjective skill or knowledge. So we often, in clinical settings, in hospitals and things, they will rely on more objective measurements, like a fundal heart. So you can't just say, oh, yeah, it feels like a normal-sized baby. It just won't fly. But I do believe that midwives have the skill to physically feel a very large or a very small baby with their hands if they've honed that skill. But it's not something that's generally valued. And I fear it might be a lost skill that maybe that's just where I am in my little bubble here in Australia.

[13:16] Okay, so let me tell you a little bit about the accuracy of fundal height measurements because I do remember talking to a midwifery colleague who sort of said to me like, is there any actual research around fundal height? Yeah, of course, we do them every time, but why do we do this? Is there any research? So, of course, I was very curious as well because it became, it's a fundamental part of our midwifery care. So, I was curious to know, is fundal height measurements evidence-based and accurate way of determining the size and growth of a baby? So, of course, I went and found out. I'd never really thought about it because, again, it's super ingrained in practice but here we go so.

[13:59] The research says that fundal height measurements can detect either a very small baby or a very large baby, but only 50% of the time is it accurate. So 50% of the time, a very big or a very small baby is missed if you just use fundal height alone. So that's the accuracy of it if you're looking over a large group of people. But we as clinicians can increase the accuracy of this technique by measuring the baby from the fundus to the pubis and by our technique being consistent, which is what I was saying earlier. If you do the same exact thing every single time, you will personally increase the accuracy of your measurements, especially if they're done on the same woman over their pregnancy. So we can increase the accuracy if your technique is consistent and you measure from fundus to pubis. because what the research showed actually was that less experienced midwives have a higher level of inaccuracy. So when they looked at some of the research, it can get as with less experienced

[15:08] clinicians, it can get as low as 17% to 30% accurate in inexperienced midwives. But then when they looked at the data on the experienced midwives, they found that it can get up to as accurate as 88% of the time midwives accurately detecting a very large or very small baby.

[15:26] So first, the clinician's experience makes a difference to how effective this particular technique is. And the other thing is that it adds accuracy if the same clinician is doing it each time with the same woman. So if you have continuity of care with your midwife and she's seeing you all through your pregnancy, there's the same midwife measuring your fundal height every single time and she's doing the technique exactly the same every single time, then we can consider that measurement a more accurate measurement than if it was somebody different at each appointment because everybody's got a slightly different technique there is going to be discrepancy as we can see in the research and also this measurement of fundal height is not a one and done type measurement if you do it the one time it gives you very little information the information and value of it is over time as you can chart the growth of the baby and see if it's consistent.

[16:23] Sometimes women's fundal height is consistently two or three centimeters lower or higher than their usual gestation. And if that tracks normally, then that's normal for that woman. Whereas if you measure one time and the woman is measuring three centimeters above or three centimeters below her gestation of what you're expecting the measurement to be, that could be alarming. But it only has meaning in the context of the rest of the measurements. A one-off measurement is not a valuable way of determining the size of a baby. It has to be done over time and plotted.

[17:02] And as I said earlier, the fundal height measurement very casually, very loosely correlates to gestation. So if you measure your fundus and you're 30 weeks pregnant, you'd be measuring 30 but three centimeters above or three centimeters below is still considered within a normal fundal height range and again this becomes important as we're measuring over time.

[17:26] This would be an unusual finding. Let's say hypothetically, your client is 30 weeks pregnant. You measure her fundus one week and her fundus is 27 centimeters. You can write that down as normal. But then maybe you see her again in two weeks and now it's 33 centimeters. Also considered normal. However, in the context of the previous measurement, a growth of six centimeters in two weeks is an unusual growth pattern. One which you would have never known had you not had a previous history of her fundal height measurements. So this is where some clinical reasoning comes into play.

[18:06] So the Australian College of Midwives does suggest that three centimetres above or three centimetres below is considered normal. However, you do need to apply some clinical reasoning to that and have a look at the pattern of growth. And some other things to consider here when we're looking at what a normal fundal height is, is that fundal height can be a less accurate way of measuring if the woman is carrying some extra weight. So if you're a bigger girl, obviously, there is a little bit more weight. So that would be part of the equation as we're determining your normal fundal height. And obviously, if there's two babies in there, then you're going to have a higher fundal height. Or if the baby is not lying in an up and down position, if it's transverse, you're going to get a completely different fundal height. So if you're a clinician listening you can or you can personally increase the accuracy of your fundal height measurements if you standardize your technique so the standard technique is that you start the measurement from the top of the fundus and you bring the tape measure down to the pubic bone and you do this with the tape measure facing down so you can't see the numbers it's considered a more accurate way of doing things so you're not tempted to fudge the results as you're doing it And obviously, the more you do, the more experienced you get, then you keep doing your technique over and over again. It becomes regular and similar.

[19:29] And then your midwifery skill will help you to more accurately detect a larger or smaller baby. Remembering to always put your hands on the woman's belly and feel the size and position of the baby as well before you go ahead and do fundal heights. So what we currently know in the research about fundal height measurements is that there's not actually a lot of the research is what I found. And you can have a look in the resource section for this podcast episode if you're on the mailing list every week we'll send out a link to all the resources you can get those for all the back catalog as well but if this is something that interests you you can have a look at the research that we've already found but it is an easy and low-cost tool that can be applied by midwives in any setting really any country around the world particularly that if they're under resourced or highly resourced countries this skill is universal and it's been proven that when midwives are good at it and the model is effective, such as continuity of care, then it's a useful clinical tool.

[20:34] And it's also an expected professional standard. So actually, even if there was no research and we discovered that there was very poor reliability, we'd be required to do it anyway. That's the situation. So it's our professional standard. Might as well get good at it. So if you're a woman listening, expect to have your fundal height measured at each appointment. Which the other thing I've noticed is that if you're having obstetric care where the obstetrician has access to an ultrasound in their rooms and every time you go in instead of putting their hands on you and feeling your baby and measuring your baby manually they might just put the ultrasound on instead and they might not even put their hands on you. I've seen obstetricians almost some obstetricians I'm not all not all obstetricians there are some excellent ones out there who are very thorough but some I've witnessed to almost poke and prod the woman with the tips of their fingers, not wanting to sort of fully engage with that experience. I don't understand it, but I'm a midwife, not an obstetrician. Maybe we work differently. But often they're relying more on ultrasounds than what they could feel in their hands. But this is not an evidence-based strategy. We know that repeat frequent ultrasounds are not what's recommended in the standard antenatal care guidelines. And it's not an accurate way of determining size or growth, which we will discuss, shortly.

[22:00] So regardless of access to ultrasound, your care provider should be putting their hands on your belly to get a feel of the size of your baby and its position, and also measuring with a measuring tape. This is the very first level of screening to determine the size of your baby.

[22:15] And I think fundal height is something that everyone can understand. In fact, women could learn to do this themselves. And I always explain to my clients the rough idea of a fundal height. And so it's language that we can use to discuss the growth of their baby in a way that they'll understand so if they know that it's approximately one centimeter of growth per week of gestation but that three centimeters above and three centimeters below is still considered normal and I measure their fundal height and I say great you're measuring 32 centimeters and they're 30 weeks pregnant they immediately know okay that's a normal fundal height alternatively it can be a way for me to communicate pathology to my clients. For example, and this has happened to me before, I've seen a client once and they were 32 weeks pregnant, measured their fundus, it was normal. Two weeks later when they came, it was 38.

[23:09] Immediately I was able to say to her, the growth of your baby is unusual over this two weeks. To me, this feels like there's an issue. She immediately understood that yes, there appears to be an issue. She didn't just have to take my word for it. It was an easy way for us to communicate that this might be a good reason for an ultrasound, for example, and she had already felt in herself that something wasn't right. And so it's something everyone can understand, whereas an ultrasound, you're looking at a picture that you don't fully understand and you've got to take your clinician's word for it that something is either right, wrong, or your baby is big or small.

[23:49] Whereas want to take a moment here to just encourage and speak to clinicians. I just want to encourage you not to be flippant about fundal height measurements. Take the opportunity to put your hands on the, And feel for the position of the baby before doing the fundal height and really pay attention to what else you're feeling, not just for the position, how much water is there? How much is the baby moving? Is it straight up and down? Because if the baby's slightly tilted to the side or if the baby's gone down further in the woman's pelvis or is really curled up, maybe that's going to affect your fundal height, but you can explain the reason for that. Really paying attention to the palpation that you do and then follow that up with a really accurate and consistent method for fundal height measurement means you could trigger the need for more monitoring if something is unusual but also if you're careless in doing it and then you find something unusual you might accidentally trigger off further monitoring that the woman might not actually need all because you weren't diligent in checking the position of the baby carefully or in developing your skills. And more than once, I have found a serious medical issue with just palpation and fundal height measurement alone.

[25:11] And had I not taken these skills seriously and trusted what I was feeling under my hands and was fully present while doing the assessments each time, I may never have followed up on the findings if I wasn't so confident and sure about my skill and consistency in those techniques. And also, I listened to my midwifery intuition that said, this feels different and unusual to last time, and I know I'm good and consistent at fundal heights, and I know I've paid attention very carefully to what each woman's individual belly and baby normally feels like. So you can immediately start to determine when there's deviations. I realize this is the blessing of working in continuity of care. I guess what I'm trying to say is this is not a soft skill. It's a powerful one. And as I said, at least two times, I have detected with only my hands and the flundle height measurement some serious issues with babies that required further monitoring and some pretty heavy interventions. And that was all because I'd worked very hard to understand each individual baby and I knew what my skill level was with flundle height measurement. So I always encourage midwives and maternity care providers to do these things mindfully and consciously and systematically.

[26:35] So then, now, let's move on from fundal height. I know I've gone on about this for a little while, but we're talking about big babies, small babies, and this is one of the first and clearest ways we can work out the size of your baby. So the next way that we can determine the size of your baby is through ultrasound.

[26:55] The research on this says that an ultrasound is accurate 70% of the time. So if you ultrasound 100 babies, 70 of those will receive what's considered an accurate weight estimation. However, I know that might sound pretty good. However, the problem is, is that acceptable accuracy of an ultrasound for weight and size is within 10%. So if you have an ultrasound and your baby is 4 kilos and the acceptable margin of error is 10% plus or minus your baby's actual weight, your baby, who is 4 kilos on ultrasound, could be 4.4 kilos or could be 3.6 kilos. And that's considered an acceptable margin of error for a growth scan. So 70% of the time, an ultrasound can detect the size and weight of your baby within 10% discrepancy. That's considered accurate. So 30% of the time, it's even more widely inaccurate than that. So 70% of the time, they can get the baby's weight plus or minus 10% and to the medical establishment, that's acceptable. That's considered an acceptable margin of error. So when they say that ultrasound is accurate 70% of the time, what they're saying is we can estimate 70% of babies within 10% plus or minus.

[28:20] That's the accuracy of ultrasound. So if someone says to you, yes, they're accurate 70% of the time, their definition of accuracy is plus or minus 10%. It's not we can accurately determine the exact weight of your baby. It's we can accurately determine it within 10% of its actual birth weight, only 70% of the time. The other 30% of the time, it's way out of that range. And because of this, the research says that ultrasound is not good enough, as a clinical decision-making tool because of how poorly it can estimate the weight of your baby. So by ultrasound, only two in three babies can be accurately sized within 10% accuracy. So the research is not in favour of using ultrasound as a clinical decision-making tool for sizing because of its inaccuracies. We get this from the Cochrane Database of Systematic Reviews.

[29:15] What you're likely to encounter is your clinician with an ultrasound telling you that your baby is either too small or too large and using that to recommend an intervention potentially. Could be an induction, could be a cesarean section, could be further growth scans, but the research is not on that side. It's not in favor of routine growth scans for women who are at low risk of very small or very large babies. So potentially, if you are at a high risk of a very small and very large baby, serial ultrasounds are what's going to be recommended to you. However, the research is not in favor of that for women who are at low risk of that.

[29:55] And there's research that's spoken to this. They've actually looked at this and routinely giving everyone, every woman, a third trimester ultrasound didn't improve outcomes at all. But it did increase interventions as a result of what they find. Because they're inaccurate, if they do a third trimester ultrasound for no particular reason, they're going to find something that alarms them and intervene. However, by doing this, they didn't improve the outcomes for the babies, but they intervened a whole lot more. So in the research, they applied an inaccurate ultrasound to all women and then started acting on these inaccurate results. And this is what the research is currently warning us against, is please do not use ultrasound as a clinical decision-making tool in isolation because it doesn't improve outcomes, particularly for low-risk women, and it does increase interventions. And the research talks about other things in the fact that it's actually a wasteful use of a resource to be giving large groups of women who are low-risk.

[30:58] Ultrasounds it's wasteful it's not cost effective and to expect every single pregnant woman to somehow be able to access an ultrasound at 36 weeks is considered an unreasonable level of maternity care considering it hasn't actually demonstrated itself to improve any sort of outcome and we saw things like this introduced during covid because there was reduced actual care for women they decided some bright spark i don't know decided 36 weeks let's just send them all for an ultrasound. It wasn't evidence-based. They did it anyway. So we should really be saving this technology for women who actually need it and who actually might benefit rather than just doing ultrasounds on every single woman and multiple ultrasounds of pregnancy. It's hard enough to get an ultrasound appointment as it is. Women who actually need ultrasounds have trouble getting in on time probably because we're overusing the tool to give to women who don't actually need it. And it's not even that accurate. So all of the stats I'm giving you, they are based on actual research papers. So again, if you are curious to read this for yourself, you do not have to take my word for it. I'm just kind of summarizing everything that I read. But you can get access to the actual research papers that I've used to create this podcast episode. Feel free to read them. They're all plucked out of the research papers. You just have to be on the mailing list at melanethemidwife.com.

[32:23] So, what we know is there's no accurate way for a clinician to accurately tell you if you have a very large baby or a very small baby until the baby is out.

[32:36] That's when we can give you the accurate weight and size of your baby, not while it's in. So, if you've gotten the word from your care provider that your baby is so big that it's not going to be able to come out, or maybe because of the massive size of your baby you need to have a cesarean section or your baby's so big that we're worried about the growth we need to give you an early induction just know that no one it doesn't matter how good they are how skilled they are can accurately.

[33:07] Determine the size of your baby not until it's out however something that ultrasound could potentially help with is if your baby, let's say your baby is small for gestational age, that's a thing. That means that all parts of the baby are small equally and your baby is proportionally small. But if it's intrauterine growth restricted, if your baby is growth restricted on the inside, which we're going to talk about the reasons why your baby could be small like this, although the ultrasound results are still not accurate for weight, they can give you measurements of the baby, the head versus the baby's tummy versus the legs. And if your baby's head, for example, is on the 50th centile, but the rest of the body is on the 10th centile or the other around, there's some big major discrepancies that might be worth exploring and looking at more closely. Growth restricted babies rather than small babies is pathological. So growth restriction is always pathological and it could be a result of something being wrong. But small babies are not always unwell babies. Some are just constitutionally small but otherwise healthy.

[34:15] But the real win for ultrasound is that it could detect a growth-restricted baby and it can also check the function of the placenta. So here's where maybe ultrasound could be really helpful as a clinical tool. So we can't completely throw out the use of ultrasound, but the thought is that we shouldn't be making clinical decisions on a single growth scan without considering other ways of checking in the previous history of clinical care, fundal height measurements, other ultrasounds. One single ultrasound that says your baby is too big or too small is not a reason to do anything. All it is is a reason to explore the next strategy of monitoring or not. In the show notes below, I've created this whole package of all the different pain management strategies that I've ever seen women use during labor and birth that I used myself. I've been a home birth midwife for 18 years and I've collected all of the strategies that women use to work through the pain of labor so that they can avoid pain medication. So I've created a guide to giving birth without pain medication. And the whole idea is that you get an opportunity to tap into this amazing physiological experience that your body is gifting you.

[35:31] So if you go to the show notes, you can purchase that for yourself. It's only $27. It's like cheaper than lunch. It's barely a thing, but also in there.

[35:42] I've included a whole section on how your partner and support people can apply the strategies that I've mentioned in the guide to giving birth without pain medication. They will also be able to help you work through it because it's all well and good. If you already are prepared to work through birth without pain medication, but all the people on your crew, on your team who are there to help you give birth are doubting you and encouraging you against it and pushing you towards pain relief then they could sabotage your birth so in there I've also put a whole little section for your support people and your partner to listen to so that they also have the strategies to know how to help you so if you want to tap into the possibility of bliss during your labor and birth go to the show notes click the link to the guide to giving birth without pain medication you can get it for yourself it's only $27 it's it's as I said cheaper than lunch and it can give you all the strategies that you need to avoid pain medication in labor and birth. But there are some other ways. So of course, that is jam-packed full of information. But if I was going to give you a little bit more here in this podcast episode, how do you tap into the bliss of labor and birth? So the first thing is to avoid pharmaceutical pain relief. And all those strategies are in the guide to giving birth without pain medication.

[37:03] Okay, now let's have a look at the reasons why your baby might be big or small. So there can be completely normal reasons for why your baby might be small or big. So even if someone says, right, you've got a small baby or you've got a big baby, let's look at the reasons why that actually might be completely normal and fine for you. So firstly.

[37:25] Women of different ethnicities make different size babies. So standards are catered to currently white Western demographics. So most of the time, unless you're looking at research, and there are research papers that seek to create different growth charts for different ethnicities, that's what we really should be working towards. Because each ethnicity would have a different range of normal for the size of their babies. It's individualized. There's unique growth expectations and size expectations for different ethnicities.

[38:00] So it's a really actually fundamentally racist idea that everyone's baby should conform to a Western standard of normal, white Western standard. And if the babies don't fit this white Western standard of normal, then they're considered there's something wrong that needs fixing. And I know some people might look at this and say, oh gosh, Mel, it's not racist. But, you know, if you deem something wrong because it doesn't conform to a dominant Western idea, then that disadvantages and belittles what's true for people of other ethnicity and it demonstrates racism, a preference based on race. The one size that is considered the right size is the white western sizing. And the other sizes, if they're either much smaller or much larger, are considered wrong or too big or too small because we're using white western measurement.

[38:58] To represent what is right and appropriate. So women of other ethnicities fall out of this white Western normal range. The size of their baby is considered wrong or pathological. So yes, it's discrimination based on race or ethnicity, but it's in built into the maternity care system. So don't hear me saying, I'm not saying here that individual clinicians are personally racist, But the system in which they work is built upon this racist idea that the white western standard is right and anything that falls outside of it is wrong or pathological. When we know that different ethnicities have different normal weight ranges. So individual clinicians might not be personally racist, but by assuming that white western standards of baby size is correct, we're subconsciously upholding the racist approach that's built into the modern maternity care system. So we can't just apply this blanket so that your baby's too big, your baby's too small, because some ethnicities and some women will naturally make smaller babies and some will naturally make bigger babies. But we can't pathologize that against a Western standard.

[40:18] But that's one reason why you might make smaller or bigger babies. Your ethnicity, just genetics. My family makes typically smaller babies. I expected to have smaller babies. So maybe your mom did. Maybe your sisters did. And maybe you're just a healthy woman with a bigger or smaller baby on board. And some places, there's a word for this. They're just constitutionally small or constitutionally large infants, which means that's just how they are. There's no particular issue. Maybe your body just makes smaller or bigger babies. They're just constitutionally small or constitutionally large because that was always how you were going to make a baby. That's always the size your baby was going to be. There's not an actual issue that's causing your baby to be too small or too large. That's just how they are. That's just the size baby that you grow for your genetics, for your ethnicity.

[41:20] So those are two reasons why you might be growing a different size baby. But you can't work all this out until they're out of your belly. So unfortunately, there's this ambiguity, you know, mystery while you're pregnant. Is this just normal. However, there are abnormal or pathological reasons for why your baby might be small and this is where it's worth looking into it. The size of your baby is not a diagnosis in itself. You've got a small baby is not a diagnosis. That's an opportunity to look into why. Why is my baby small? Is the baby small because it's pointing to a bigger issue that needs addressing? The size of the baby is almost irrelevant in this. This is just a symptom of something that needs further investigation.

[42:05] So let's start by asking why a baby might be small and.

[42:10] Is it because there's a problem? It's not just, hey, your baby's small, let's get it out. Your baby's small, let's find out why. So if you smoke or use drugs or there's particular medications that have a similar effect, having these things, we know that the babies are smaller. They weren't going to be constitutionally smaller. They're smaller because there's a problem, particularly smoking during pregnancy. So it periodically restricts blood flow through the placenta. So it essentially malnourishes the baby in small increments over its gestation. So it reduces nourishment and oxygen supply to the baby at periodic times during your pregnancy. And so statistically, babies who are born to women who smoke are smaller.

[43:03] If you're smoking using drugs or particular medications, that might be a reason why your baby is small. And passive smoking can have a similar impact. And consider if you're working in an industry with poisons or fumes, these could also have an impact on the size and growth of your baby. And this is why we ask as clinicians about environmental hazards and substance use in pregnancy, because it can impact upon the function of your placenta, how much oxygen and nutrients get to your baby.

[43:36] And interestingly, there's actually research on how smoke, passive exposure, passive smoking, it actually impacts different ethnicities differently. So there's been some research on this and black women seem to have experienced a bigger impact upon their pregnancies if they're exposed to secondhand smoke compared to white women. So they've done this with a few different ethnicities in a few different locations and found that the way that different bodies retain the product, the products of the secondhand smoke, you know, the smoke that you would inhale through passive smoking, it's different across races and cultures just because of genetic makeup. So we have to be studying race, different ethnicities with the same topic needs to be addressed across different ethnicities. You can't just have a homogenous study group, which only has a few ethnicities in it. So the issue is, is that we haven't really diversified research. We focused too smallly, that's not a word, smallly, shallowly on typically white Western women. And the problem is, is that then this research is applied in the clinical setting and we don't have five different guidelines depending on ethnicity. So if the demographic of where you work and your maternity care service, if your maternity service includes a high number of Iranian women and Indian women and Japanese women and Tongan women, for example, Oh.

[45:06] There are not going to be four separate guidelines depending on each ethnicity. So even if the research is there, it's not being applied in a logical way. You're starting to see the issues here with using ultrasound and standardized research to care for a diverse population of women. So that's the issue with systematic maternity care is there's one system and it's just supposed to be a blanket, one size fits all. But it's not true because we are all different. So that's one reason you could have a small baby for pathological reasons. So substance use in pregnancy.

[45:41] Now, the other one that is kind of new, and I feel like in the last few years, it's the increased use of the nuchal translucency ultrasounds as more than a routine test done for genetic abnormalities. So the nuchal translucency ultrasound is done between 12 and 14 weeks. And it was originally marketed as a way of screening for Down syndrome or it's a genetic screening and they give you a risk ratio. I'm not going to go into the details. You can have a listen about the details of the nuchal translucency on episode 147 which is all about screening options but with the nuchal translucency ultrasound there's a blood test that goes with it when they do the ultrasound and they use the blood test and the findings from the ultrasound to make conclusions. However, the blood test, and this is what I'm interested in, the blood test that comes along with the 12 to 14-week ultrasound, there is placental hormones that they measure, one of which is called PAP-A.

[46:44] So if you have a low PAP-A below 0.4, they discovered that a low PAP-A puts women at more risk of having growth-restricted babies or smaller babies. They're also at higher risk of preterm birth and also preeclampsia. So there's something in that sometimes they recommend that women, particularly if you've had multiple miscarriages or multiple preterm births before or a history of low birth weight babies. And then they also identify that you've got low PAP-A on your blood tests with your nuchal translucency. I'll sometimes recommend routine use of aspirin through your pregnancy.

[47:25] And that's thought to increase blood flow through the placenta. So PAP-A and placental hormones could be low because it speaks to the quality of the implantation of your placenta of the placenta. The baby grows the placenta and then it implants into your uterus and there's placental hormones that can indicate, they can point to a possibility that maybe implantation has not been optimal and now you've got reduced levels of placental hormones and this theoretically could result in poorer function of your placenta and therefore a smaller baby. So if you've got low pap A and a history that you can draw on that indicates that maybe for a reason this might be happening for you could be a pathological reason, you might have had preeclampsia in the past, for example, or a family history of preeclampsia.

[48:20] Then this could be worth looking into. And for women who have low papay, sometimes they will offer serial or routine growth scans. Serial, not like breakfast cereal. Repeated routine growth scans. So that they can build up a picture of the growth of your baby. However, we know that the accuracy level is only 70% of scans are accurate. And that accuracy is considered 10% above or below the weight of your actual baby. Again, I'm not saying if any of this is right or wrong. I'm just giving you the heads up on the options that will be presented to you. So if there is a question about placental function, either that they discover on ultrasound or through the blood tests, then you might be offered aspirin as a way of counteracting this situation. And then you might need to consider more scans or some medication. So if you're listening to this ahead of time, now you're aware of the things that you might be asked to consider.

[49:25] Again, not necessarily saying it's right or wrong to get the PAP-A result or the nuchal translucency. I guess it just gives you some information about your possible risk factors and then you can make decisions about how you want to act after that. Okay, so the next abnormal or pathological reason for why your baby might be small is if you have high blood pressure through your pregnancy or preeclampsia. The root of these problems is thought to be placental, which explains why the babies are at more risk of being small and this also manifests with high blood pressure, preeclampsia and HELP syndrome. But the issue has probably been simmering for some time. So placental insufficiency is another one for why your baby might be small. But again, that's usually a result of one of the conditions that we just spoke about. It might not be in itself the thing that started it. It might be a symptom of what's going on, the size of your baby. But anything that reduces the blood flow and activity of your placenta is going to impact the size and development of your baby. If the placenta was not adequately implanted and is suboptimal, if there's substance use and the blood flow to the baby is reduced throughout periods of the pregnancy, then that's going to impact the baby's size and well-being.

[50:43] So next, if your baby has a health condition or a developmental abnormality or a congenital genetic abnormality, that can impact on their growth. So again, ultrasounds can tell you some of this and some babies are born with syndromes or genetic syndromes that can take time to diagnose that maybe we don't actually have a screening test for and some are more rare things and you may never discover what the genetic combination is, but for a baby that's got genetic abnormalities or developmental abnormalities, they can come across on ultrasound as small. Again, this is just an indication that something might not quite be right. The size is a symptom, not a diagnosis.

[51:30] The other thing that can give you a small baby is if you have an infection, a maternal infection, such as syphilis, toxoplasmosis, CMV, so cytomegalovirus. So if your baby's born very small, they can do what's called a torch screen, T-O-R-C-H screen, which tests the baby for multiple viruses that could have impacted upon its growth. The other thing that can give you a small baby for a bad reason, not for just a normal constitutionally small baby, is maternal nutrition or calorie restriction and starvation. So literally for women who have eating disorders during pregnancy or who are calorie restricting in order to maintain some kind of unrealistic weight expectation or obviously in less resourced countries where women don't actually have enough food during their pregnancy, this impacts the size of your baby. If you malnourish yourself, if you starve yourself, you also starve your baby. For some women, this is unavoidable. For others, they're intentionally doing this to control the size of their baby.

[52:38] So what we might do now is talk about what kinds of interventions are offered to women who are diagnosed with smaller babies and we will cover big babies as we go as well. But first, I wanted to talk about small babies. Okay, so let's go hypothetical. You've presented to your care provider and you're 36 weeks and they say, hey, your baby is small. We want to induce you to get the baby out. We're worried about it. We want to give you an induction.

[53:09] I know this sounds weird. Look, it sounds weird to me too. So they say to you, hey, your baby's small. We think we should get it out. People go, hang on, so my baby's really small, so you want to get it out of me? Wouldn't it be better to keep the baby in so that it grows more?

[53:27] So it doesn't make a lot of sense on the surface. But what they're saying and what they're subtly saying is that your baby's small. We want to get it out of you because they think that something in your body is a danger to the baby and that a better job could be done when your baby's out. Or you can do a better job at looking after your baby when it's out instead of in. And part of this is that care providers are not very good at dealing with uncertainty. Certainty they cannot tell you for sure a lot of the time that your small baby is a result of something wrong and pathological in your body and so if the baby's out there's a lot more certainty they can see it and they can measure it and they can check it and they can see how much food is going in and what's coming out so part of it is wanting to increase the level of certainty about what's going on they're not comfortable with not knowing if and why your baby is small and so the reaction is, well, maybe if we get it out, we could know for sure. And if they want a result, and so they might want to resolve it by getting the baby out. The issue is, is that if you bring out a constitutionally small baby unnecessarily through the process of usually induction.

[54:43] Then you're doing a massive disservice to that baby, to that already potentially little baby. It needed more time with its mama and it needs to get full term and a mature size. And then the earlier you bring babies out, we start to have issues of prematurity. So we increase the burden to the healthcare system by bringing these well, constitutionally well, but small babies out early. And we know that we can't accurately diagnose size. A very, very small baby by ultrasound or even by fundal height, we could determine it if it's very, very small or very, very large.

[55:23] But it asks the question is, should we be bringing small babies out, especially now with the newer research showing the detrimental long-term effects on children when they're born before 39 weeks and before they're ready? Their brain isn't ready yet. And we know that there has been a habit of inducing small babies without an accurate way to truly measure the size of a baby in utero. So there's definitely a movement from researchers and clinicians who are fighting to keep babies in until at least 39 weeks. Now that we know how important those final weeks of pregnancy are for the long-term health and cognitive development of the babies. But there is a difference between getting a small healthy baby out for no particular reason and then making decisions about when to give birth to a baby who's suffering from intrauterine growth restriction. So if they suspect that your baby is growth restricted and then for example an ultrasound is done and they can see that placental blood flow through the placenta is also restricted and there are clear issues with the placenta and potentially the amniotic fluid is low.

[56:32] These are the babies that might benefit from coming out sooner. Maybe there is a problem. But constitutionally small babies whose placentas are functioning beautifully, you have normal amniotic fluid, we need to be more critical about thinking about birth decisions. Is this a constitutionally small baby that's otherwise well? We don't have a problem. Is the baby growth restricted and there's a problem with the placenta? That's a whole different story. We're aiming to get those babies out, of course, before they're further compromised. But there's a fine line.

[57:08] And the issue is, is that more and more babies are being born preterm, not because there's an issue, but because there's an increase in induction for

[57:14] younger and younger babies. So that's the rationale. There are some genuinely growth-restricted babies that maybe would do better on the outside. But the problem is, is that we can't accurately diagnose the size of the baby until it's out already. And then in hindsight, we could say, well, we're glad we got the baby out or that one was actually fine. and although when we used ultrasound as a tool to make a very big decision to induce the baby that didn't need to be induced. I've seen this happen before. I've had clients who have been told whoa your baby is super small. I recall a client who had twins and they kept telling her that one of the twins is really small we've got to get the babies out and they were pressuring her over and over and she finally agreed to a cesarean section and when the babies came out, The babies were exactly the same size. She was so angry of how much pressure was put on her about the size of the baby. And then it led to her decision to have a cesarean section and the babies came out almost identical size. They did not need to be born. So you've got to be asking questions of your care provider. Is my baby growth restricted?

[58:31] Is that what you're worried about or is it just small? And then can we use this opportunity now, if you think there's something wrong with my baby, to check levels of pap A? Is there any other screening we can do to work out why my baby is small? Do I have a risk factor for this? Is there a good reason to start acting and changing the gestation for the baby to be born? Maybe there's a placental issue. Maybe there's a substance use issue. Maybe there's a nutritional issue. Or have you always grown smaller babies? Has your mum grown smaller babies? What ethnicity are you? What's your diet like? Those are all the things we need to consider when we consider growth of the baby. Just an ultrasound is just not enough of clinical reasoning to make decisions about induction or cesarean section before you go into labour.

[59:21] Okay, that's what I've got to say today about small babies and determining size for smaller babies. There's lots of beautiful papers in the resource folder. That you can have a look at and I'd encourage you to read the full research papers if you're considering.

[59:38] The information that you might need to make some decisions for yourself. So now we're going to dive into a big baby's chat, kicking off with abnormal reasons why your baby might be big. So we've already worked out some normal reasons for why your baby might be big and healthy and fine, and that includes ethnicity and genetics. And it's just supposed to be that way. Your baby's constitutionally large. You're growing that size baby because your body can do it and you're well and healthy. In which case, you don't have to worry about it because that's the size that your body is going to grow because it knows that it can get that size baby out and that's what you were made for. That was always the size baby you were going to grow.

[1:00:19] So that's the main reason for why you'll have a big baby. It's because it's supposed to be big because that's how your body grows babies and that's the size that's going to fit out. Unfortunately, we don't know that until hindsight. But the more babies you have, the more experience you'll have about what your body's capable of. The problem is, is somebody might try and pathologize this situation.

[1:00:40] But there are abnormal reasons for why your baby might be big. And the issue is not that it's big. The bigger issue is that it's too big for your body and it's bigger than it's supposed to be. It's a bigger baby than what your body would have normally made had your baby not had health issues or had you not had health issues. And the main reason why women would grow a bigger baby is gestational diabetes. And obviously.

[1:01:10] The gestational diabetes diagnosis is fraught with controversy, and we've got a whole podcast episode on that. And I've put the link to the gestational diabetes episode in the show notes if you want to have a listen to that. So if you've got a bigger baby and you've got gestational diabetes, consider those gestational diabetes episodes. But if you have true diabetes and it's uncontrolled or undiagnosed, your baby is at risk of growing bigger than it should have. And this is only true for uncontrolled diabetes and undiagnosed diabetes. For women who are listening who have gestational diabetes or type 1 diabetes, type 2 diabetes, if you've been diagnosed with it and you're doing your blood sugar levels every day and you're maintaining your blood sugar levels within a normal range and you're checking in with your care provider, all your sugars have been normal, all your blood sugars have been normal. You're managing your insulin if that's what you're on. You're working with your diet if it's diet controlled. You're doing some exercise to keep all the levels stable.

[1:02:12] You have what's called controlled diabetes. And you don't have a risk of an abnormally large baby because you're managing your risk factors. You controlled the issue. Congratulations. Well done. You had an issue, but you're doing the work to control it. And all of your efforts are going to pay off because you are not at risk of growing a bigger baby if your blood sugar levels are stable. So, controlled diabetes does not grow bigger babies.

[1:02:45] And therefore, this is the reason why I don't think some clinicians will tell you completely different because often in hospitals, women at 38 and 39 weeks, if you're gestational diabetes diagnosed as just having gestational diabetes, you'll be lined up for an induction regardless of how well your blood sugars have been controlled. But if you control your blood sugar levels, you've also managed the risk and therefore you're not at risk of a larger baby. But uncontrolled and undiagnosed diabetes, that's where the issues are. All right, so the next reason why your baby or the next abnormal reason for why your baby might be big is for women who've just got poor eating habits and have gained a lot of weight in pregnancy as a result of those poor eating habits. I'm not talking to you if you've gained a lot of weight and you're eating healthily. This is not a fat shaming segment. If you're eating well and healthily, you cannot control the rest of your whatever your body's going to do. But if you're a woman who has a high diet of sugar, processed foods, packaged foods, you are typically going to grow a bigger baby because you're eating a lot of junk food and gaining a lot of weight as a result. I'm not just saying this out of the blue. There's research on the amount of sugar and size for babies. I'm just saying women who eat poorly, high sugar diets, high carb diets, and who are not looking after themselves in pregnancy, your babies are going to be bigger.

[1:04:14] Or, and this is the other catch, is you might be having high calorie but low nourishing diet, which could subsequently give you a smaller baby. But certainly if your diet is causing you to gain an unusual amount of weight during pregnancy, then this also will be happening for your baby. Again, this is not a fat shaming segment. It's not what I'm here for. I'm just saying that if this has been your pattern is not to nourish yourself well and you have a high sugar diet and a low nourishing diet, then this is the same impact as it's going to have on you is the same impact it has on your baby.

[1:04:51] There is weight gain that happens in our pregnancies that we have absolutely no control over. So I'm not talking about that. I'm not talking about just because you gained weight when you're pregnant, you're going to have a baby who's larger than it should be. That's not what I'm saying. But the research shows that for women who have eaten poorly and gained an abnormal amount of weight during pregnancy as a result of that, same thing happens for your baby. High sugar and high processed foods are the problem, not the weight gain.

[1:05:21] All right, so the next thing, and this is kind of obvious, but for pregnancies that go beyond 42 weeks. So the longer you're pregnant, the bigger your baby gets. Babies don't just stop growing. While they're in there, they're always growing if they're well and healthy. So the longer you're pregnant, the bigger your baby's going to be. It's not necessarily an abnormal thing, but being pregnant past 42 weeks is considered abnormal. So if you're past 42 weeks, that's an abnormal reason for why you have a bigger baby. So consider that, you know, it does put you at a, if you're going beyond 42 weeks, you're also at risk of having a baby that's bigger than usual. So these are three abnormal reasons.

[1:06:04] So why do we worry about big babies? We already had a chat about why we worry about smaller babies. If you have a smaller baby, it could be a sign that placenta's not functioning well. Maybe that baby is constitutionally small, the placenta's functioning well, they don't need to come out early. But with the growth-restricted babies, we need to determine, is there an actual issue that we might need to get the babies out early?

[1:06:28] That's why we worry about smaller babies. But why are we worrying about bigger babies? Why is everyone obsessed with trying to work out the size of your baby? And if it's big, just like if it's small, they want to get it out because they're worried that your baby's big for an abnormal reason or that your body's incapable of actually giving birth to a baby of that size. We can't really know that until you actually give it a go, but that's the worry. And the reality is, is that if you're diagnosed with a baby that's over four kilos at full term or above the 90th centile for its gestation, then your care provider is likely to recommend an induction to get your baby out early or even more severely. They might tell you that your baby is so big that they don't believe it's going to come out of your vagina. And they might want to take you for an immediate cesarean section, not even off of the option of induction simply due to the size of your baby and some assumptions they've made about the adequacy of your pelvis. And that's why it's important to start working out, is my baby big?

[1:07:34] Because it's supposed to be? Or is there a problem? Or could there be a real issue with how they're diagnosing big babies? Because we already learned that ultrasound is accurate 70% of the time within 10% plus or minus 10%.

[1:07:53] So why the big deal with bigger babies? We'll talk about the first thing and that is shoulder dystocia. So what you'll be told is that a bigger baby means that there's more risk of shoulder dystocia. And I've looked at so many shoulder dystocia papers to try and actually disprove this statement. What women are told is that the bigger your baby gets, the more risk there is of you having a shoulder dystocia. And you know, I'm like, no way, women's pelvises can do it. Babies come out, size doesn't matter. But unfortunately, and I'm here to tell you, that bigger babies do have an increased risk of having a shoulder dystocia the bigger they get beyond 4 kilos. So if you have a baby between 2.5 kilos and 4 kilos, and here is where I think they changed the range. They used to say over 4.5 kilos was a big baby, but now they're saying it's 4 kilos. And I'm pretty sure this kind of research is why. So if your baby's between 2.5 kilos and 4 kilos at birth, obviously we can't work that out until the baby's born, 0.6% to 1.4% of these babies that are between 2.5 and 4 kilos will experience a shoulder dystocia at birth. So pretty rare, 0.6 to 1.4% if they're in that weight range.

[1:09:22] For babies who are over 4 kilos, the stats go up to 5% to 9% of bigger babies. Babies who are over 4 kilos will experience a shoulder dystocia and it's exponential. So the bigger the baby gets, the more likely it is to happen. So the closer to 4 kilos you are is the lower percentage options. And as they get bigger and bigger and bigger, the risk goes up.

[1:09:49] So these are some Cochrane reviews that have compiled the data. This is where I got this information from. So it's pretty damning research. And I kept pushing this episode off historically because I kept looking for more research that maybe they didn't have it right. Sort of like, please tell me it isn't so. So what the Cochrane review did, and this is a 2023 paper, so it's the most up-to-date thing we've got. And it's called induction of labor at or near term for suspected macrosomia. So the research paper compiled research all about induction for full-term babies or near term, near full-term babies that were suspected of being big, suspected macrosomic babies. And it showed that if you induce women who had suspected macrosomia, so suspected large babies, their babies were approximately 200 grams lighter, which is no surprise because they bring them out early. And also the rates of shoulder dystocia were less in the induction group than they were in the group that was just observed. So they didn't do anything to one group and the other group they induced.

[1:11:07] Now, I don't know what the events were around the physiological birth of the bigger or suspected big babies because they were not all definitely bigger. But what they did see was a reduction in shoulder dystocia with the early induction for the babies who were suspected of being big. But, and here's the interesting part, the researchers did not recommend routine induction for babies who are suspected as macrosomic, even though they found these stats. Even though, yes, inducing women early whose babies are suspected to be large does reduce shoulder dystocia, but it also increases the risk for a whole lot of other stuff. So the argument is, is that we can't, firstly, we can't accurately diagnose macrosomic babies. And therefore, we shouldn't be routinely inducing them. This is what the Cochrane paper says.

[1:12:01] If you choose an induction, though, statistically, you are at reduced risk of shoulder dystocia, but you increase your risk of other things like postpartum hemorrhage, prematurity, and the possibility of an unnecessary induction. So don't use this as a reason to just induce women because this is actually still very controversial. So the Cochrane article said, yep, we could reduce it a little bit. However, consider the fact that induction introduces a whole lot of other risks that women need to consider before deciding how they're going to weigh up their risks. Also, they argued that because of the significant downfalls of ultrasound and how inaccurate they are and that the fact that we don't have a good enough information to accurately diagnose the size in order to confidently use induction as a strategy for macrosomic babies that we shouldn't be doing it there's we're not good enough at diagnosing macrosomic babies yet to confidently be inducing them so i guess what i'm trying to say and what cochran said is that a bigger baby does have an increased risk of shoulder dystocia. Remembering that clinicians are pretty good at dealing with shoulder dystocia. It's not always a big emergency. And if you induce that bigger baby earlier.

[1:13:27] That it reduces the risk of shoulder dystocia because it also theoretically reduces its size. We definitely need an entire episode to talk about shoulder dystocia and we do have one of those and I've linked it in the show notes. So if shoulder dystocia is something that worries you, have a listen to the shoulder dystocia episode. The link is in the show notes.

[1:13:48] But what the point of this discussion has been is that the reason why everyone is panicking about big babies is that they're frightened that your baby is going to have a shoulder dystocia and they want to avoid it by bringing your baby out before it gets too big but they can't really accurately diagnose how big your baby is and that's where the issue lies. Okay maybe if we could accurately diagnose larger babies maybe an induction could prevent a shoulder dystocia or you know there could be a percentage of babies that we could prevent from getting stuck but while we're reducing that risk we're introducing a whole lot of others. And that's the issue. And I think that's what Cochrane is saying is how do we justify reducing the risk of shoulder dystocia by using induction when we know that induction carries a whole collection of other risks. And you can listen to the induction episodes that I've done. Again, I'll tag those in the show notes below. So you're just moving the risk to another spot. You're kicking the can further down the street by potentially reducing the chance of shoulder dystocia, you're increasing the risk of a raft of other things happening.

[1:14:58] So although maybe an induction meant that women didn't have a shoulder dystocia, but then they also created a whole lot of other issues and increased a whole lot of other risks. So now it's up to you women to decide which risk you're willing to take. This is just information. I'm not telling women what they should do. So that's what I'm going to say about that. And that is the Cochrane paper and it'll be in the resources so everyone can have a read of it. But I will say one more thing, that the next reason why people get all panicky around big babies is there's another thing that's called kefalopelvic disproportion or CPD, kefalopelvic disproportion.

[1:15:39] And kefalopelvic disproportion is when, you know, we've all heard for some women being told your baby's so big that it won't fit outside of your pelvis and therefore we're not even going to attempt an induction we're just going to give you a cesarean section we think your pelvis won't fit your baby out so this is the worst of it really this is a complete disbelief that the baby's even going to fit through the women's pelvis and so women get worried in there oh my gosh, my doctor said, or someone said, this baby won't fit through my pelvis and therefore I need a cesarean section. But I am here to tell you that we cannot in any way measure the pelvic inlet of a woman to determine if the size of the baby's head is going to be able to get out. There is no way of determining that while you're pregnant. So this is something that you're worried about, like maybe the baby's not going to fit, but.

[1:16:39] But we can't predict that. There's no clinical way to predict, is that baby going to fit through that woman's pelvis? Because your pelvis changes during labor and birth. Movement changes the size of your pelvis. There are some structural reasons why maybe a baby won't come through your pelvis. It's not a proportional issue. Maybe you've broken your pelvis before and it's misshapen. Maybe you've been malnourished as a child and your pelvis didn't properly develop. In countries where there are child brides and children are having babies, this can be an issue, but not for a well-nourished woman who's got no pelvic pathology. But let's say this does eventuate. Let's say you are one of those women who has kefala pelvic disproportion, where the baby genuinely, genuinely cannot fit through your pelvis. It's not very common. But let's say you are that woman.

[1:17:38] Guess what happens? The only thing that's going to happen is that your baby is not going to come out. You're going to go into labor and it won't progress normally. It'll be slow. It might be extra painful because your body's working really hard to get the baby out. Maybe your cervix will dilate but your baby won't come through or there can be a raft of other signs and symptoms. The baby might get into a level of distress or you just won't be able to continue to progress and in hindsight or during the labor as things develop you might be able to diagnose the possibility that you're experiencing kefala pelvic disproportion and if that is genuinely what is happening thank goodness for cesarean sections because your baby wasn't going to come out it's very rare and I'm really only convinced that I've seen this three times in my career as a private midwife. But if your baby isn't going to fit out of your pelvis, you can only know this in hindsight. There's no way to determine that before labour. So with true cephalopelvic disproportion.

[1:18:49] The baby won't come out because it's truly not the right size to fit through your pelvis. But we can't know that ahead of time. If your clinician says your baby's too big to fit through your pelvis, they can't know that. There's no way to know that. There's no way of determining if the baby's head is going to fit through the pelvis before you actually try. So if you're keen to try, chances are the baby is going to fit through your pelvis. But if by chance it doesn't, this is when we're grateful for cesarean sections. And careful of pelvic disproportion can be clearly diagnosed through a collection of symptoms where we start to discover that the baby's not coping with labor and that it's not progressing the way it should. So there's no harm if somebody says your baby's too big to get through your pelvis and you really want to have a vaginal birth. There's no harm in saying well that might be so but I'd like to give it a try and if it doesn't work I'll accept a cesarean section.

[1:19:45] But a cesarean section, just because your care provider thinks your baby's too big to fit through your pelvis or your pelvis is too small to accommodate a baby, it's poor clinical practice. So take home messages around big babies or suspected big babies is that firstly, we as clinicians don't have effective tools to accurately measure the size of your baby. We can measure it within 10% of its potential size only 70% of the time. So two-thirds of the time we can tell you roughly where your baby sits on the scale of big baby to small baby and if you've been told your baby is four kilos there's a.

[1:20:29] 10% plus or minus difference. So your baby could be 4.4 kilos or 3.6 kilos. And that's if you're in the 70% of women who have been accurately diagnosed. Then there's 30% of ultrasounds that will inaccurately report on the size of your baby. And so then there's more than a 10% discrepancy. So we know that we can't properly determine the size and weight of your baby until it's out. There's no effective clinical strategy to give you the exact weight of your baby. And I know there's some women out there going, my doctor got it. Some will. Some will get it accurately. But it's not universally that way.

[1:21:16] And we also know that the research does not, the guidelines don't favour inducing women early because we suspect their baby is big. It's not in any of the Australian guidelines. The NICE guidelines also don't recommend it in the UK. And the Cochrane Database of Systematic Reviews, although they found some benefit to inducing women in terms of shoulder dystocia outcomes, they still do not recommend routine induction for babies who are suspected of being large because we don't actually have the diagnostic tools to confirm that those babies are genuinely macrosomic. And there's a difference between shoulder dystocia and a poor outcome. So although we're talking about an increased risk of shoulder dystocia, if you don't induce women who have suspected bigger babies, most can be easily resolved without injury to the baby. And I think that's the crux of why I'm doing this episode, is that the amount of intervention that women are exposed to because we think their babies are either small or big is disproportionate to the actual risks that's posed to them because we don't have very good technology to determine big babies or small babies. So we're acting as if we do and that all these things that we do to women are...

[1:22:31] An exact science but potentially we're responding in fear and using poor screening techniques that don't work accurately and now women are exposed to more and more interventions to bring out their potentially small or potentially large babies. So if you're a woman listening we've got to remember that the thing that your care provider might be scared of doesn't necessarily have to be the thing that you're scared of. So even though they might want to induce you because they're frightened of shoulder dystocia because maybe your baby's on the large side, you might be more frightened of an induction than you are of shoulder dystocia. And that means your choice of how to proceed will be different. You might choose to accept the risk that maybe your baby's big and that your baby might be at risk of an increased risk of shoulder dystocia. But maybe a shoulder dystocia is not the worst thing in your mind when you consider an induction or cesarean section. And so that's for you to think about. Which risks are you willing to accept? So risk is always about perception, it's not fact. The risks that you're willing to accept and that seem too high will be different to that of your clinician. So it's all about what you perceive to be the most risky thing. Risk is not absolute, it's a perception.

[1:23:55] Okay, that was a big episode. What I feel that you can take away from this is that we're yet to be able to start recommending routine inductions for large babies, that the size of your baby is a symptom, not a diagnosis. It's an opportunity to look further in what's going on. Is there something wrong or is your baby constitutionally small or constitutionally large because our ability to actually determine the size of your baby is not

[1:24:27] particularly accurate. However, we can use the size of your baby as an opportunity to start exploring further if there is an issue. So if a care provider is recommending induction to you and you have no existing risk factors for having an abnormally large or an abnormally small baby, for example, but if you've got something, then maybe when you start to build the picture together, you can make decisions based on a whole raft of things, not just a single individual ultrasound or a single diagnosis of a potentially small, potentially large baby. Is there an actual issue? That's the question that you need to have answered before you start deciding on intervention or no intervention.

[1:25:12] There may be merit to bringing out growth-restricted babies earlier than term. Maybe they would do better and we'd prevent things like stillbirth. But the same cannot be said for healthy, constitutionally small babies for all the reasons that we've spoken about earlier in the episode. And if you do want any of the information or research papers that we spoke about in this episode, get on the mailing list at melanethemidwife.com. You're on the mailing list for this podcast and you will get access to the resource folder, which has all the catalog of research from all previous episodes as well. And I just want to remind you here that I've got a very cheap, it's only $27, a course on how to get through labor and birth without pharmaceutical pain relief so that you can give yourself the opportunity of tapping into that bliss and high of labor. Just tap on the link below in the show notes to get my guide to giving birth without pharmaceutical pain relief. This has been this week's episode of the Great Birth Rebellion podcast. I'm Dr. Melanie Jackson, and I will see you in the next episode. To get access to the resources for each podcast episode, join the mailing list at melanethemidwife.com. And to support the work of this podcast, wear The Rebellion in the form of clothing and other merch at thegreatbirthrebellion.com.

[1:26:32] Follow me, Mel, @MelanieTheMidwife on socials and the show @TheGreatBirthRebellion. All the details are in the show notes.

Episode 186 - Is your baby too big or too small?

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