Ep 34: Everything You Need To Know About Having a “Big” Baby

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Macrosomia is the term used to describe a baby who’s significantly larger than average newborns. When a baby weighs more than 9 pounds 14 ounces at birth (4500 g), the baby is considered “big” or macrosomic.

When a baby is suspected to be big, this increases the risk of vaginal injury and labor abnormalities for the mother and possible injuries such as shoulder dystocia for the baby. 

Join me today as I talk about everything there is to know about macrosomia. Learn the risk factors that come with having a bigger baby and what can be done to manage it. 

What causes the baby to grow excessively? Can we even prevent it? Find out more as you listen into this episode!

In this Episode, You’ll Learn About:

  • What it means when we think your baby is big
  • Possible outcomes when your baby is suspected to be big
  • Terms commonly used for babies with excessive growth
  • The difference between macrosomia and LGA
  • What causes a larger than average birth weight
  • The risk factors for macrosomia or having a big baby
  • How your OB/GYN physician determines when your baby is big
  • Uncommon and common complications from having a bigger baby
  • What should you do when your baby is suspected to be big
  • How we manage babies who are suspected to be big

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Speaker 1: In today's episode, I'm talking about what happens if we suspect that your baby is big.

Speaker 2: Welcome to the All About Pregnancy and Birth podcast. I'm you're host, Dr. Nicole Calloway Ranking a board certified Ob Gyn physician, certified integrative health coach and creator of The Birth Preparation Course, an online childbirth education class that will leave you feeling knowledgeable, prepared, confident, and empowered going into your birth. Quick note, this podcast is for educational purposes only and it's not a substitute for medical advice. See the full disclaimer at www.ncrcoaching.com/disclaimer.

Speaker 1: Hello and welcome to another episode of the podcast, episode number 34. Thank you for spending some time with me today. On this episode I am talking about what happens if there is a suspicion that your baby is big. I'm going to cover what the definition is. We call it macrosomia. That's the official term for it. I'm also going to talk about what are your risk factors or what are the risk factors for having a big baby. I'll talk about what are the problems that are associated with having a big baby, what are the risks for you and what are the risks for your baby, and then finally I'll end with what are the various options for management when we suspect that a baby is big.

: Now before we get into the show, let me tell you that this episode is brought to you by my free online class, How to Make Your Birth Plan the RIGHT Way. Right now I'm doing this class live and women really find it helpful. In this class I cover two of the most important factors in your birth experience. You really need to know these. I cover some tips to approach the process of making your birth plan. I go over questions to ask your doctor before you write one single word of your birth plan, some tips to get doctors and nurses to pay attention to it and then finally what to include. So you can sign up for this free live class at www.ncrcoaching.com/register. Now because the class is live, I don't do it often, usually only two to four times a month or so.

: And the best way to know when the next class is going to happen is to be on my email list. You can sign up for my email list at www.ncrcoaching.com/email and there are other benefits to being on my email list. Of course, I send a weekly newsletter where I give an inspirational quote related to pregnancy. I also give a helpful tip related to pregnancy and of course I don't spam you or sell your information or anything like that. So you can register for the class that talked about www.ncrcoaching.com/register and hop on my email list at www.ncrcoaching.com/email and of course both of those links will be in the show notes.

: All right, so let's talk about what happens when we suspect that your baby is big. So first things first, what does it even mean when we think your baby is big, what's the definition? Well, two terms are commonly used for babies with excessive or more growth. The first one is macrosomia, and macrosomia is growth beyond a specific weight and usually that cut off is 4,500 grams. So a macrosomic baby is a baby that weighs more than 4,500 grams and that's nine pounds fourteen ounces. We use grams a lot in obstetrics, but then you know, pounds and ounces are more commonly used in the u s and we use grams because it's more consistent across various countries. Grams are actually a more standard measurement across the world. Now, like I said, most of the time we use 4,500 grams, nine pounds fourteen ounces, but some organizations or textbooks, you'll see we'll use 4,000 grams and that's eight pounds, 13 ounces.

: Now the other term that's used is LGA or large for gestational age, and what that is is a birth weight that's greater than the 90th percentile for a given gestational age. So, for example, if your baby is born at 37 weeks and the birth weight is greater than the 90th percentile, when we compare that weight to all babies born at 37 weeks, then that baby would be considered large for gestational age regardless of whether or not the baby is a certain weight.

Speaker 1: So you see the difference. Macrosomia is a specific weight cutoff, whereas LGA or large for gestational age refers to a birth weight that's greater than the 90th percentile for a given gestational age. Those terms get used interchangeably. That's why I'm telling you both of them, but really it's more macrosomia that we focus on or that we use in clinical practice, that specific defined cutoffs. And you'll hear that as I keep going through the information in the episode.

: Now, the reason that we pick those specific weights is because we know that the risk for problems goes up at 4,000 grams, but it really grows up after 4,500 grams and it definitely goes up after 5,000 grams. 5,000 grams is 11 pounds and after 5,000 grams in addition to the problems that I'm going to talk about in just a second, that it can happen for mom and over 4,500 grams over 5,000 grams. There's also an increased risk of a stillbirth, and then a baby being born alive and then dying. Now big babies are not common in the US. 8% of babies born in the US weigh greater than 4,000 grams and again that's pounds, 13 ounces and only 1% are greater than 4,500 grams or 9 pounds, 14 ounces, so it's not very common.

: So what are some of the risk factors for macrosomia or having a big baby? I'm just going to list them off here. One is if you have diabetes before pregnancy, that increases your risk. If you have diabetes that develops during pregnancy and it's not very well controlled, that will increase your risk of having a big baby. If before pregnancy you were obese, that increases your risk. If you gain a lot of weight during pregnancy, another thing that will increase your risk of having a big baby. If you gain weight in between pregnancies, that increases your risk. If your pregnancy goes beyond 42 weeks, that increases your risk. And then finally, like many other things, if you've had it before, it increases your chances of having it again. So if you had a big baby before then it's quite possible or likely even that you may have a big baby again.

: Now when we looked into how those factors influence things, like which ones matter more than others, it's kind of hard to say for sure, but we know there are three things or so that we know for sure weigh a little bit stronger. So if you've had a bigger baby before, that certainly increases your risk. If you were obese before pregnancy, that confers higher risk and if you gained a lot of weight during pregnancy, that will also increase your risk more perhaps in some of the other risk factors that I mentioned.

Speaker 1: Now, how do we decide that, okay, we suspect that a baby is big? Now a true accurate diagnosis can actually only be made after birth when the baby is weighed. You can't tell for sure for baby's big till the baby's born. Now during pregnancy there are a couple things that we do to try and get a guess for whether or not we think the baby is big and you'll be surprised to hear that one is not actually any better than the other. So number one is ultrasound. Ultrasound is very commonly used to estimate a baby's weight. However, it is very, very imprecise, particularly in the third trimester. I know there are a lot of doctors who, I shouldn't say a lot, but there are some doctors who do like ultrasounds routinely, kinda in the third trimester to see how much the baby weighs and they are actually not very accurate at all and certainly not recommended.

Speaker 1: Now the other thing that we can do to estimate whether or not a baby is big is just put our hands on your belly and feel and get an estimate and feel for how big the baby feels. There's certain maneuvers that we can do, they're called Leopold's maneuvers to determine how big we think a baby is and just putting our hands and feeling is just as accurate as ultrasound. One is not any more accurate than the other. Now it may be a little bit more challenging if you are overweight or obese to feel how big the baby is, but ultrasound can also be challenging in those circumstances too. Now interestingly, studies have shown that women who have had babies before, they can predict their baby's weight just as well as ultrasound or physical exam. So you may find that if you've had a baby before, your Dr. may ask, how do you feel this baby compares to your other baby in terms of size? Because how you feel is actually pretty accurate.

: Now, although ultrasound is not good at predicting if a baby is big. So what I mean by that is if you have an ultrasound and it says, oh, the estimated weight is 4,300 grams, it's actually not that accurate. But what ultrasound does seem to be good at is predicting that a baby is not big. So if you do have an ultrasound and it shows your baby is you know, 3,700 grams, then it's actually pretty likely that your baby is not big. So that's where ultrasound may be good. If it doesn't suspect that your baby's big, then your baby probably is not big. However, if it suspects that your baby is big, it's not very accurate.

: So what are the things that we worry about in terms of complications from having a baby that is bigger? So I'm going to talk about mom first and then I'll talk about baby. So for mom, the biggest thing, or I should say the most common thing, is labor abnormalities. And by that I mean that your labor can be slow or it can even stop. And because of that, it increases the risk for cesarean delivery. This can be a little bit tricky because when we suspect that a baby is big, then studies show that there's a little less tolerance for letting labor go longer and the c-section rate increases even if the baby turns out not to be big. So what happens is we suspect the baby's big, we watch labor and it's like, oh, it's going a little bit slow. Something's off, something's not right, and then it ends up being a c-section and then it turns out that the estimate was off anyway and the baby's not big. That's not uncommon that that happens.

: Also, there may be some psychological effect of telling a mom that her baby is big. Maybe she starts to get worried that labor is not going to progress well or that a c-section may be more likely. Or should she just get a csection off the bat? So there certainly is a psychological component to it as well as to why that cesarean section rate may be increased. The other two things that can happen for mom are postpartum hemorrhage, so bleeding after birth is higher for moms that have bigger babies and then significant vaginal tears. Vaginal tears can be first, second, third, or fourth degree. First are the most minor, not a big deal. Fourth are the most severe where the vagina is torn and your rectum is torn. Like everything is torn all the way through and you can understand why a bigger baby may increase the risk for those significant vaginas tears. You got a bigger baby coming through the vagina, more chances that things are going to be injured.

: So let's talk about then what happens or what are the risks for baby? The most serious complication or risk is something called a shoulder dystocia, and a shoulder dystocia is when a baby's shoulder gets trapped underneath the pubic bone. So what happens is the head comes out, the head delivers and then the rest of the body does not come out because that shoulder is just stuck behind the pubic bone and the baby can not come out. This is a true medical emergency. If it's not relieved in a certain amount of time, then it can cause some serious longterm effects for baby. Fortunately, it's not something that happens very often, but it can happen and the risk is higher in pregnancies where baby's big. I'll talk about those numbers in a second.

Speaker 1: Even though you know there's that severe risk with shoulder dystocia, those aren't common. The more common things that are possible that could happen are injuring the brachial plexus. The brachial plexus is the network of nerves that send signals from your spinal cord to your shoulder, arm and hand, and sometimes those nerves can be stretched or injured and it can cause weakness or even paralysis in the hand or arm that's affected. There's also a possibility of breaking the clavicle, which is the collarbone or the humerus, which is the long bone in the arm. Now those sound pretty scary, but thankfully both brachial plexus injuries and fractures usually resolve with no long term problems. But again, in rare cases it can be more serious and lead to paralysis of the arm, bones don't heal well or shoulder dystocia can result in brain damage or death.

: Now I talked about what can happen for baby, shoulders dystocia also has a little bit of increased risk for mom. It does increase the risk of postpartum hemorrhage as well as those more severe third and fourth degree tears. And then some of the maneuvers that are used to help free that shoulder, they can cause nerve injury in mom's legs and in rare cases, a separation of the pubic bones, something called pubic symphysis separation, which is very painful and takes a long time to heal. Now, as I said, shoulder dystocia is not very common. It happens in about 3% of all deliveries. And actually most shoulder dystocias happen in babies that are of a normal weight. However, once a baby weighs more than 4,500 grams, then the risk can go up to about 14% and with diabetes and a baby weighing more than 4,500 grams, the risk can go up to even as high as 50% in some studies. So 4,500 grams, the risk of shoulder dystocia, 14 or 15% and then with diabetes, if 4,500 grams it can be 50% and the reason for that difference is that babies of diabetic moms, they are shaped differently, their fat is distributed differently and it tends to be more concentrated around the shoulder area. So that's why we think anyway, that babies with diabetic moms have a higher risk of shoulder dystocia.

: Now, although shoulder dystocia is the worst outcome that can happen as a result of a big baby, there are other things that can happen to babies that are big, they can have low five minute apgar scores. The apgar score is the score your baby gets at one minute of life and at five minutes of life it takes into account your baby's appearance, your baby's heart rate, your baby's grimace, their activity, their respiration rate and comes up with a score from 0 to 10 and babies that are big can have lower five minute apgar scores. And we know that low five minute apgar scores can predict a risk of problems down the line like brain development and those kinds of things. Bigger babies that are at a higher risk of having respiratory problems, low blood sugar and NICU admission. And then finally babies that are born bigger are more likely to be overweight and obese later in life than babies that are not macrosomic.

: So let's end with how we manage babies that we suspect to be big. Now one question to consider is can we even prevent this in the first place? Is there something that you know that we can do to prevent this from happening? And unfortunately there's not anything that we know of for sure that will prevent a baby from being big. Now of course we can't prevent all babies from being big. There are some babies who are naturally just going to be bigger. That's just the way things happen. But there is a study that showed that exercise for one hour, at least three days a week beginning in the first trimester in pregnancy that did help prevent babies from being big. So exercise may be something that helps exercise is going to be good for you in general. So here's another reason to, you know, optimize your health during your pregnancy.

: Now one thing that we know for sure that we shouldn't do or there's no evidence that it helps is labor induction. Labor induction has never been shown to improve outcomes for moms or babies when there is a suspicion that baby is big. It doesn't make sense, right? Because you would think that if you induce labor then the baby's not going to be able to grow anymore. So you can try to prevent problems before the baby gets any bigger, but studies do not show that it makes a difference, so it's not recommended by the American College of Obstetricians and Gynecologists. However, you will see that it is very, very, very frequently recommended or offered by obstetricians. Many, many Ob doctors will recommend induction because we suspect that a baby is big and quite frankly, if you're 39 weeks, then it's okay to offer induction or at least talk about it.

Speaker 1: There shouldn't be like an intense pressure to do it or hostility if you don't, and there really is no evidence that it makes a difference, but if you're 39 weeks in, you know you want to be induced or want to discuss induction, then that's not unreasonable for sure. Especially if your cervix is favorable and we determine that by Bishop's score where we look at how dilated, how face your cervix is, the position of the baby, if it's soft, the position of your cervix, if you have a favorable bishop score and you're 39 weeks and suspect that the baby's big, certainly not unreasonable to talk about induction.

: Now c-section is offered or I would say even recommended ACOG uses sort of loose language. They say c-section is considered at a certain point. I'll give the numbers in a second, but in practice we tend to recommend a c-section if a baby is greater than 5,000 grams or 11 pounds in a non-diabetic mom or greater than 4,500 grams in a diabetic mom and that's nine pounds, 14 ounces. And again, that difference, diabetics have a lower threshold or cutoff because of the way the fat is distributed on babies. So 5,000 grams or 11 pounds for a non-diabetic mom, a c-section is offered, 4,500 for a diabetic, 9 pounds, 14 ounces. And a lot of women, to be honest here, those numbers in the light, wait a minute, you're telling me that you think that my baby is going to be Tim Pounds, 12 ounces or 11 pounds, 15 ounces will say well yeah, I want to have a c-section. I'm not trying to have some that big come through my vagina. There's nothing wrong with that at all. So it is totally a discussion that you have with your doctor. About what is the best option is keeping in mind that it's possibility on the other side, that the estimate was wrong.

: Now, c-section definitely reduces the risk of birth trauma, but it does not eliminate it. Babies can still have brachial plexus injury at the time of c-section or other types of birth trauma, even broken bones, so it reduces it but does not eliminate the risk. If you do decide that you want to go for a vaginal birth, then the things that we do during labor are that we tend to not be as aggressive, for lack of a better word, with Pitocin, we're not gonna like slam tons of pitocin in you in order to try to get your labor moving. You know, we tend to actually have more of a hands off approach if we suspect that the baby's big, you know, either baby's coming or baby's not.

: Also, we don't do operative vaginal deliveries, so no vacuum or forceps because that increases the risk of shoulder dystocia, postpartum hemorrhage. So we do not typically do a vacuum or forceps if we suspect that baby is big. Ultimately, however, how suspected big baby is managed is based on a number of multiple factors and it's really individualized. So for example, if you have had a big baby before, like the biggest baby that I delivered, and this was a woman having her first baby where we did not suspect that the baby was big. First baby and her baby weighed 11 pounds 2 ounces and she pushed that baby out with like no problems. It was a very easy, straightforward delivery. Well in her, for a future pregnancy, if it's suspected that her baby is 10 pounds or 10 and a half pounds, nobody's going to be all that alarmed because she's already pushed out an 11 pound baby with no problems or a different scenario. If it happens to be your first baby and we suspect that the baby is big, but you haven't gained a ton of weight during your pregnancy, you weren't obese before you started your pregnancy and it turns out that maybe your mom delivered vaginally two 10 pound babies without any problems, well then, okay, we're feeling pretty good about your chances of having a vaginal delivery with no issues.

: However, if you were obese before pregnancy and you've gained a lot of weight during pregnancy and you've developed diabetes during pregnancy and your blood sugars haven't been under the best control or we've had trouble getting them under control, well then those are all red flags that, mm, you know, maybe vaginal delivery is not the best option. So it's really an individualized approach as to how we manage a suspected big baby.

: All right, so just to summarize, macrosomia, that's the official term for a big baby is growth beyond 4,500 grams. Usually that's 9 pounds, 14 ounces or some say 4,000 grams, 8 pounds, 13 ounces. Ultrasound is not good at predicting whether or not a baby is big. It is however good at telling us whether if a baby is not big, c-section is recommended when a baby is suspected to be greater than 5,000 grams or 11 pounds in a non-diabetic mom and greater than 4,500 grams in a diabetic mom, that's 9 pounds, 14 ounces. Induction is not recommended. It doesn't improve outcomes, but if you're 39 weeks or more, it's not unreasonable to consider it. And then finally, the management is very individualized because it depends on a number of factors.

: All right, so that is it for this episode of the podcast. Be sure to subscribe to the All About Pregnancy and Birth podcast in Apple podcast, formerly known as iTunes or wherever you listen to podcasts. And ladies, I would be so appreciative if you would leave me a review in iTunes. It helps the show to grow, it helps other women to find my show and plus I just really love reading the things that you say. So if you would leave me an honest review in iTunes, I would really, really appreciate it.

: And don't forget about my free online class on how to make your birth plan the right way. You can register for that at www.ncrcoaching.com/register. I do not offer the class that often because I do it live. I only do it anywhere from two to four times a month. You can sign up for my email list to get notified when the next class is going to happen. That's www.ncrcoaching.com/email and those links of course will be in the show notes.

: Now coming up on the podcast, I have two back to back episodes on Preeclampsia. The first one is a very difficult birth story for lack of a better way to put it as a really, really tough story. And the second episode after that will be an expert interview with the maternal fetal medicine doctor who's really gonna break down Preeclampsia for us. So come on back next week. And until then I wish you a very healthy and happy pregnancy and birth. Today's episode is brought to you by Women's Wellness Coaching by Dr. Nicole Calloway Rankins. Head to www.ncrcoaching.com to check out my free one hour mini course on how to make your birth plan as well as my comprehensive online childbirth education class, The Birth Preparation Course, with over eight hours of content and a private course community. The Birth Preparation Course will leave you knowledgeable, prepared, confident, and empowered going into your birth. Head to www.ncrcoaching.com to learn more.