Ep 83: Fetal Growth Restriction – What It Is, How We Screen for It, and Risks You Should Know

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I've gotten quite a few requests to talk about this week's topic, so today I'm doing a deep dive on fetal growth restriction (AKA intrauterine growth restriction) and everything you need to know.

Fetal growth restriction happens when a baby hasn't reached its growth potential inside the uterus. This can happen for several reasons that I'll dig into today, including genetic causes, something going on with the placenta, or something going on with mom. Growth restriction isn't straightforward or universal, and sometimes babies are naturally small, so it's important for you to be prepared just in case your baby experiences FGR.

I'll talk about how we screen for fetal growth restriction, some of the issues and questions about percentiles we use, and what the risks can be to baby and mom both during pregnancy and after birth. I will also walk you through what we do after this diagnosis so you know exactly what to expect. 

In this Episode, You’ll Learn About:

  • What fetal growth restriction is
  • Why there is a difference of opinion in the field about what percentile to use to diagnose FGR
  • What asymmetric vs. symmetric growth restriction look like and how they affect baby differently
  • Why it's important to remember that some babies are just naturally small and may not be diagnosed as experiencing growth restriction
  • How growth restriction can affect baby during pregnancy and throughout life, and how they can impact mom
  • How we screen for growth restriction and why it is important to monitor baby's size as they grow

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Nicole: On today's episode of the podcast, I'm talking about fetal growth restriction.

Nicole: Welcome to the all about pregnancy and birth podcast. I'm Dr. Nicole Callaway Rankings a practicing board certified OB GYN. Who's had the privilege of helping hundreds of moms bring their babies into this world. I'm here to help you be knowledgeable, prepared, competent, and empowered to have a beautiful pregnancy and birth. Quick note, this podcast is for educational purposes only, and is not a substitute for medical advice. Check out the full disclaimer @ncrcoaching.com/disclaimer. Now let's get to it.

Nicole: Hello, welcome. Another episode of the podcast. This is episode number 83. Thank you for spending some of your time with me today. So in today's episode of the podcast, I'm talking about fetal growth restriction. It's also known as intrauterine growth restriction. I've had a few requests to talk about it recently. So I decided to go ahead and add this in, since it seems like a few folks are curious. So on this episode, you will learn what fetal growth restriction is. And I tend to save fetal growth restriction as opposed to IUGR intrauterine growth restriction. So what fetal growth restriction is, and it's not exactly straightforward or universal, what the definition is, you'll learn the risk associated with fetal growth restriction, both during pregnancy and for the baby. Once the baby's born, how we screen for growth restriction, again, not necessarily straight forward, how we manage growth restriction during pregnancy, and also during labor and birth understanding growth restriction is one of those things that you need to know about just in case it's not likely to happen, but if it does, you have some understanding of it and it's not so scary and overwhelming as a result.

Nicole: And of course helping make things not so scary and overwhelming is a really important part of why I make this podcast. And I know it's something that you appreciate too. I got this really lovely review from E Franny B on Apple podcast. And it says the title of the review is my favorite pregnancy podcast. And the review says, this is definitely my favorite pregnancy podcast. Dr. Rankins provides evidence without bias to help moms to be make well informed decisions that work for them. I want my birth experience to go a particular way, but Dr. Rankins helps me understand when and why particular interventions might be necessary. And I think I'll feel less confused and scared if I'm faced with those interventions, please keep making the podcast. Well, thank you. Thank you. Thank you, E Frannie B for that really, really lovely review. Yes. Helping reduce confusion and fear is definitely one of the reasons why I make this show and as a huge part and purpose of my work now, of course, the podcast is one way that I do that, but not feeling confused or scared as also one of the things you'll get after going through The Birth Preparation Course, The Birth Preparation Course is my signature online childbirth education class.

Nicole: That ensures that you are calm, confident, and empowered to have a beautiful birth through my unique five step beautiful birth prep process. You will go from feeling scared and overwhelmed to feeling ready for your birth. You can check out all the details of the birth preparation course at NCRcoaching.com/enroll at is currently 40% off to help, make it affordable during these challenging COVID time. So again, check that out in NCRcoaching.com/enroll. I would love to see you inside the course. All right. So let's get into today's show about fetal growth restriction. So fetal growth restriction, or FGR also known as entry uterine growth restriction or IUGR is the term that we use to describe. And we say fetus when the baby's still inside mom, that sounds so impersonal to me. So I often switch out fetus for baby, just because it feels, I don't know, a little more like personal.

Nicole: So it's a term that's used to describe a baby that has not reached its growth potential inside the uterus. Now, the most common definition that we use for growth restriction is based on ultrasound. And what that is is when the estimated weight is below the 10th percentile for the gestational age and that point in pregnancy. And this is only for in the second half of pregnancy. So as an example, if we estimate the growth at 28 weeks and when we plot it against other babies and how they've grown, if your baby is in the 10th percentile or less than we would consider that baby to potentially have growth restriction. Now, although we use the 10th percentile as the most common definition, sometimes we use the less than fifth percentile or less than third percentile. And that's because using percentiles is a little bit controversial. So let me explain what I mean.

Nicole: So when we use that percentile, in order to define growth restriction, there are a couple of potential issues with it. One, it doesn't distinguish between a baby who just happens to be naturally small. There's nothing wrong with the baby. The baby's just on the smaller side naturally versus a baby that is small because of a pathologic process that has kept that baby from reaching their full growth potential. Okay. So actually as many as 70% of babies that are estimated to weigh below the 10th percentile on ultrasound. So as many as 70% that are estimated to be below the 10th percentile based on ultrasound measurements, they are actually just small because they were naturally made to be small. So maybe mom is small. The parents are small. Her other kids have been totally normal, but are just small. So up to 70% are, are likely small just because of those, those what we call constitutional factors.

Nicole: And they are actually not at risk of having any problems. So when we use this 10th percentile cut off, there's this possibility of misclassifying, these normally nourished and healthy babies as having growth restriction from a processes, that's keeping them from reaching their growth potential. I hope that makes sense. I know it can be a little bit confusing, so that's why some people use fifth percentile or third percentile instead, because we know that on the really smaller end, those babies are more likely to actually be growth restricted. Okay. Now the other reason that the 10th percentile or that using percentiles in general, rather can be controversial is that it doesn't distinguish whether or not a baby may be above the 10th percentile, but is actually smaller than it could be. Okay. So what if you have a baby that is in the 15th percentile for instance, but in that, by that number, they would be okay.

Nicole: But actually if that baby wasn't being affected by some sort of process, that baby would actually be in the 30th percentile. Okay. So when we use the 10th percentile, we don't catch those babies who are actually estimated by the percentile to be okay, but they're not, they're not reaching their full potential because of an issue that's going on. Okay. So that's the other concern with using percentile. And then the final issue with using percentile is that when you do percentiles, you're comparing it to other references and there's little consensus on which references we should use. So there've been different populations where they take a big group of low risk women and kind of plot all those babies weights out that's called a standard reference curve. Or sometimes they take like a general sampling of the population, a population reference curve in to compare how your baby stacks up against this particular population or reference.

Nicole: And it's hard to know if those reference standards are actually the right ones that we should be using. Okay. That's a really hard thing to sorta figure out. So one of the things that has been proposed is actually comparing babies to their own growth over the course of the pregnancy, as opposed to comparing a baby to a big population of other babies. I hope that makes sense. Okay. So those are the issues with percentile. I know it can seem a little bit confusing, but I wanted to give you a little bit of background on why it's not always straight forward and why this 10th percentile is a little bit somewhat of an arbitrary number that has some, uh, it's open to interpretation. Now, nevertheless, we still do know that tracking the baby's growth is something that is important. And I will say that honestly, most folks still use that 10th percentile cutoff.

Nicole: That's kind of what we've gotten used to doing what we base our studies and data on. So that's most likely what you're going to see, but I do think it's important for you to know some of that backstory. Okay. So regardless of whatever definition of growth restriction is used, what percentile cutoff, then it's either classified as what's called symmetric growth restriction or asymmetric growth restriction. So symmetric growth restriction accounts for about 20 to 30% of fetal growth restriction. And that refers to a growth pattern where all of the organs are decreased proportionally. And that is because of some global issue that is affecting the entire baby. That is usually thought to be a result of a pathologic process that started early in pregnancy and it's affected how the entire baby is growing. So that occurs in about 20 to 30% of growth restriction and then asymmetric growth restriction comprises the vast majority of growth restrictions, so that 70 to 80% of it, and what that usually is characterized by is a decrease in the abdominal size.

Nicole: So a decrease in the liver volume, a decrease in the fat around the baby's abdomen in relationship to the head circumference. And that is thought to result from the ability of a baby to adapt to an environment inside the uterus that isn't necessarily favorable. So if there's an issue going on, what happens is that the baby will preferentially redistribute blood flow to those very vital organs, like the brain, the heart, and the placenta. Those things are important for baby to survive inside the uterus. And then it will spare blood flow to the things that the baby doesn't need as much like the abdominal organs, the intestines, the lungs, the skin, and the kidneys. So most of the time it's asymmetric growth restriction that 70 to 80% of the time. And that is an adaptation where the baby is preferentially sending blood to the organs that are most important.

Nicole: All right. So let's talk about what causes growth restriction. Well, it can be either from the baby itself. So there's an issue with the baby. It can be from the placenta. So there's an issue with the placenta, or there can be something going on with mom that's causing the baby not to grow as much. There can definitely be overlap between those, but roughly it's either an issue with the baby, the placenta or the mom. We think that actually about 30 to 50% of this is influenced by genetic factors, variations in birth weight in general. And then the rest is due to some sort of environmental factors. We also know that maternal genes will influence birth weight more than paternal genes, although both have an effect. So why do we even worry about how babies are growing and well, the reason is because it can have negative impacts on a baby's life.

Nicole: So there's an increased risk of stillbirth. When babies have growth restriction, the number is about 1.5%, which is still very low. Stillbirth in general is low, but it's about twice as high is what happens when babies are not growth restricted. And that number goes up even more to 2.5% for babies that are less than the fifth percentile when you look at their numbers. So there's definitely an increased risk of stillbirth with growth restriction. There's an increase risk of other neonatal problems like neurodevelopment problems, lack of oxygen, babies have trouble regulating their temperature. When they're born, when they're growth restricted, they have trouble sometimes maintaining their blood sugar. They also have something called Polycythaemia or they may have it Polycythaemia where there too many red blood cells in the blood. And then also they can have issues with their immune function. All of those things are more common in babies that have growth restriction than in babies that have normal growth.

Nicole: It doesn't mean that it's automatically going to happen. It just means that there is a higher risk, and it's more likely that the risk or that these things will happen. The more severe the growth restriction. So a baby, as I mentioned, who is like less than the fifth percentile or less than the third percentile has definitely a higher chance of having some of these problems occur. It's also a higher risk. If the growth restriction is early in pregnancy, the earlier that we see growth restriction, the worst the prognosis is for the baby. So some of the longterm things that can result from growth restriction after the baby is born. Sometimes they have issues where once on the outside, they don't grow as well. And then later that seems to be an increased risk of obesity, of type two diabetes. Also have heart disease, hypertension, and chronic kidney disease.

Nicole: We don't know exactly what causes this, but there's definitely research data that shows that babies that are growth restricted inside are at risk for some longterm problems as they grow up. And then finally, for moms giving birth to a baby with growth restriction can be predictive of mom having an increased risk of having heart disease in the future. Again, we don't know exactly what causes this, what leads to it, but again, moms are at this increased risk of having heart disease. So there short term risk, right around birth there's longterm risk as babies grow up. And then there's also risk for mom. So how do we screen for growth restriction? Well, that is actually a major focus of prenatal care is determining which babies are at risk for growth restriction, identifying these babies and seeing if we can do or have interventions that can reduce some of those problems occurring.

Nicole: Now, even though we've decided that screening is a good thing, and we should try to look for this as an issue, the unfortunate truth or research backed evidence that we have so far is that we don't necessarily know that screening actually works very well or that we have great interventions to reduce the frequency of any of these outcomes. It hasn't necessarily been proven to be effective. And then there are also potential harms of screening actually, including over-diagnosis of growth restriction. So like I said, are we saying babies who are actually just happened to be small, but we're saying they're growth restricted. It's not always easy to tell that, um, and that can lead to anxiety. It can lead to unnecessary testing. It can lead to induction of labor. So we have to be careful about how we look for these things. Now, even with all of that being said, we've decided that screening is better than not screening because we will catch some serious concerns and potentially avoid some bad outcomes.

Nicole: So even though we don't necessarily have all the data and evidence to show that screening for growth restriction is appropriate as collectively as a specialty, we still screen for it. It's still considered a standard part of prenatal care. So how do we screen for it? The most common approach is measuring the fumble heights. So that's when we use the measuring tape and we do that 20 weeks of pregnancy or later. So in 20 weeks, about 20 weeks of pregnancy or your uterus is about the level of the belly button roughly. So after that, we measure the distance in centimeters from the top of the pubic synthesis or the pubic bone to the top of the uterine fundus. And we use that just as simple tape measure. That's a simple, inexpensive, widespread technique that we use to detect growth restriction as well as if the baby is growing on the big side as well.

Nicole: So the first suspicion that a baby is not growing well often comes from this measurement. And what happens is we see that the length of the tape is not what we would think to be the expected size for the dates and pregnancy. Now, as far as what that discrepancy is, um, everybody defines it a little bit differently, but the most common criteria that we use, and this is what I used when I was in prenatal care, is that if there's a difference of at least three centimeters, so four or more between how far along you are in pregnancy and then how, um, what we're getting on the measuring tape, then that is a concern that the baby is small. So for example, if you're 28 weeks, but you're measuring 24 weeks, okay, then that would be something that says, Hey, we have this discrepancy. And we think that there may be an issue, and that can go either way actually, where the baby's too big or too small that, you know, four or more difference before we get concerned.

Nicole: Now how good fundal height measurement is, is also something that's controversial. One review concluded that it's not necessarily the best method. And there are some things that we can do in order to make it a little bit better. Some of the things that we know can affect it, of course our body mass index. So if you happen to carry more weight around your belly, then it's going to be a bit harder to measure the fundal height, because you're just not going to be able to feel the top of the uterus as well. Also, something else that can make it more challenging is if you have something like large fibroids that are distorting, the size of the uterus and fibroids are more common and in black women, then that may not be a good way to measure the fundal height as well. So the technique appears to work best when you can easily obviously feel the uterus, and there are no other issues that are distorting it, and it works best when it's the same clinician measuring the same person over time and using an un-marked tape.

Nicole: Okay. Because what can happen is if you know, somebody's 28 weeks and you can see the markings on the tape, that may be, you tweak it a little bit, you adjust it a little bit to get closer to 28 weeks, because that's what you're expecting. Instead if we use an unmarked tape and we just kinda mark what we get and then measure it out later, you're more likely to get an accurate reference. And then the other thing that's important is plotting it or showing it over time, if over the course of your pregnancy and ideally measured by the same person, you know, you're two centimeters off at this visit two centimeters off the next visit. Then that is kind of a consistent growth pattern and not necessarily something to be concerned that the baby isn't growing well. Okay. So that is what we use most often is fundal height measurement.

Nicole: And then we use ultrasound as an adjunct to that. If there's an issue where there's a lag detected, or we can't feel it, or again, it's not reliable like for fibroids. So in those instances, then we would use ultrasound in order to better track the baby's growth because that fundal height measurement with the tape is inaccurate. Now another potential method for tracking growth of the baby is universally performing ultrasound examination on every patient. And this is not something that's routinely done. There are some doctors who may do this, but it's not something that's recommended by a cog as something that needs to be routinely done. There's no consensus on the timing. There's no consensus on the number of ultrasounds that need to be done in general, if you are going to use ultrasound, because of the other reasons that I talked about, for instance, like if you have extra weight and we can't feel the fundal height or it's distorted because of fibroids, then you do need to do at least two screening exams after the 20 week ultrasound.

Nicole: So two additional ultrasounds after that 20 week anatomy ultrasound are considered to be ideal, but again, there's not necessarily a strict protocol or way for how things go. There has been some investigation into seeing where the ultrasound can be used as a screening approach, where we track an individual baby's growth over the course of the pregnancy. But again, that's still pretty investigational. Another thing that is also investigational in terms of screening is using three dimensional ultrasound. It does appear in some studies to be promising, to detect growth restriction because maybe it gives more precise information than standard 2D ultrasound, but it's not widely available. And it hasn't been adequately tested in large studies in order to see how it can be used. So just to summarize on the screening, most of the time we do fundal height for women who we can't measure it, or the uterus is distorted, then we do ultrasound.

Nicole: Or if there's a discrepancy based on the fumble height, then we do ultrasound. There is also a small group of women who we recommend ultrasound to look for growth restriction off the bat. And those are women who are at higher risk for fetal growth restriction. So if you have multiples, if you have high blood pressure before pregnancy, kidney disease before pregnancy, lupus, if you have diabetes before pregnancy, heart disease, sickle cell disease, smoking, then those are reasons why we would go ahead and do ultrasound to look for growth restriction. Also a few more things, poor weight gain. If, if mom is really not gaining enough weight, also our assisted reproductive technology. So IVF is something that we know can put moms at risk for growth restriction. Then we actually do do an ultrasound exam to estimate the baby's weight and look at the baby, the placenta, the amniotic fluid, usually once or twice in the, in the third trimester.

Nicole: All right. So what happens when we suspect growth restriction? So when an ultrasound suggest growth restriction, the first thing that we need to do is confirm the suspected diagnosis. So even if we see a lag on measuring with a fundal height with the tape, and that that is confirmed with an ultrasound that is suspected that the baby is small, we still need another data point in order to determine whether or not a baby is actually growing small. We need to see how the baby grows over time to determine if the baby is actually small, because sometimes though that number will change, it will be on the 10th percentile. And then the next ultrasound, it would be the 18th percentile. And in that case, it's not growth restriction. So we have to repeat an ultrasound later to see what happens. That'll also help us understand, is it a baby that is truly growth restricted and having a pathologic process, that's interfering with its ability to reach its full growth potential, or whether it's just a baby that's small.

Nicole: So if the baby has normal anatomy, if the growth trajectory is normal, if the blood flow something called Doppler studies through the umbilical artery or the middle cerebral artery, those the umbilical arterie runs to the envelope cord. The middle cerebral artery is an artery in the brain. When they look at Doppler studies through those vessels, if they look fine, if there's normal amniotic fluid, then that suggests more of just a baby who is naturally small, whether than a baby who is having their growth potential stunted. Now, when we go to look for the cause again, it can be hard to tell, but we look for maternal issues, placental issues, or issues with the baby. So first thing we start with is a complete history and physical exam to look for anything that may popup, okay. Are things that we know are associated with growth restriction.

Nicole: So just good old fashion, take a history, do a physical exam. See if anything pops up a big one that the will usually be fairly obvious as something like preeclampsia, particularly severe preeclampsia. So that would be high blood pressure in pregnancy. We know that that's associated with growth restriction. The next thing we're going to do is look at the baby. So a very detailed ultrasound survey to look for any anomalies that may be occurring with the baby that are associated with growth restriction. So some things that we know can affect baby's growth, are some, gastrointestinal malformations, um, something called Gastroschisis, which is it's a little bit complicated to explain, but basically the intestines are kind of on the outside of the body. Um, some skeletal malformations can be associated with a baby growing smaller. Some heart defects can be assisted seated with the baby growing smaller.

Nicole: So we do a very detailed look at the baby to see if there are any things that give us a clue as to why the baby may be small. We'll also look at the placenta, of course, in that instance as well, sometimes genetic studies are indicated in order to see if there's a genetic issue that may be causing the baby to be small. This is particularly the case if it happens very early. So if we notice that a baby is very small, I would say a 20 week ultrasound, then we're going to do genetic studies too. If they haven't already been done genetic studies to look at the baby's chromosome, if the growth restriction is very severe. So, less than the fifth percentile we'll look at chromosomes, or if the growth restriction is symmetrical. Also, if we see that there are other major problems going on, and so if there's issues with the heart or brain or anything, that we see then we're going to look for genetic studies with the baby as well.

Nicole: And then finally, we may also do some evaluation for infections because there are some infections with mom that we know can be associated with effecting a baby's growth. So some things that we know that are associated with growth restriction are cytomegalovirus infection, toxoplasmosis, veracela, rubella. This is why, we ask if you're vaccinated against rubella and varicella, so we can kind of cross those off the list. If we see any issues, cytomegalovirus and toxoplasmosis aren't things that women are routinely exposed to. And actually a lot of us will get infected with CMV before pregnancy. But if we see growth restriction, then we check those to be sure we can even go as far as taking a sample of the amniotic fluid in order to look for any evidence of infection around, um, the baby directly with amniotic fluid. And then a quick note about infections related to growth restriction.

Nicole: It doesn't appear so that COVID is associated with an increased risk of fetal growth restriction or increased prevalence. Uh, but we still need to continue to collect data, but so far COVID does not appear to affect a baby's growth. Now, even though we look for all these things, issues with baby issues, with mom issues, with the placenta, a lot of times we cannot always determine what the cause for growth restriction is. And it'll just be something that we don't necessarily know what the cause is. And we just follow the baby and manage the baby accordingly. So speaking of management, what happens when we confirm that a baby is growth restricted? So I'm going to talk about management and babies that are otherwise structurally normal and have normal chromosomes. Okay. If a baby has something going on with the chromosomes or has a heart defect or an issue with the brain or the intestines or anything like that, then a management may vary a little bit based on what the underlying issue is.

Nicole: So I'm just talking about management and what happens if the baby is structurally normal and chromosomally normal. And that is actually most of the time with growth restriction. What is the case? Okay, so the management of babies with growth restriction involves three things. Number one, measuring the baby's growth over time. Okay. That's something called the growth velocity. So the baby's growth over time, how the baby is behaving inside your uterus based on ultrasound, that's something called an NST or a biophysical profile. And I'll talk about what that is in just a second. And then the third thing is measuring the blood flow through usually the umbilical artery, but also sometimes the middle cerebral artery that's called Doppler velocimetry. I think I'm saying that right, but Doppler studies is what we shorten it to. And that looks at blood flow through the baby's arteries and the particularly arteries, but sometimes the venous vessels as well.

Nicole: So those are Doppler studies. Okay. So those are the three things we do track the baby's growth by ultrasound, see how the baby is behaving inside. And then also measure the blood flow through the vessels. Now, as far as the fetal growth velocity or weight assessment, what that means is that we just see how the baby's growth is over time. We plot a growth curve for the baby to see how the baby is growing over time. So usually we do serial ultrasounds at every three to four weeks or so to see how the baby is growing. Sometimes it may be two to three weeks if there's some other concerns. So if the baby is very small, like less than the fifth percentile, if the fluid is very low, if there are abnormal Doppler studies, then we may do it at two, three week intervals. But otherwise at the growth is near the 10th percentile of the fluid around the baby looks normal.

Nicole: If the Doppler studies were normal, typically we do it every three to four weeks. That gives us some time to see how the baby is growing over time. When babies look like they're growing normally, then they're probably just a baby that is small. So naturally small based on genetic factors or mom factors of that kind of thing. Okay. So that's the growth. Second thing that we do as I talked about with the non stress test and or the biophysical profile non-stress test is putting you on the monitor and just measuring the baby's heart rate for at least 20 minutes. We look for the baseline level of the heart rate, the variation in the heart rate, something called variability, and then as whether or not their accelerations where the heart rate goes up or decelerations where the heart rate goes down. So it should never be a flat line.

Nicole: It should be sort of squigglingness in the heart rate. And then the BPP is the biophysical profile and that's an ultrasound and it's using the NST plus the fluid around the baby, the baby's muscle tone, the baby's movement. So seeing if the baby moves seeing if the baby practices breathing inside in each of those things gives a score of two points. So those five factors, NST fluid, muscle tone, movement, breathing points each. So the highest BPP you can get as a 10 at anything that's an eight out of 10 or 10 out of 10 is considered good. Okay. Or if you don't have the NST, then we do it at an eight. So then a six out of eight or an eight out of eight would be good. These tests are both pretty easy to perform. And we know that they are very reliable in terms of telling us that a baby is healthy.

Nicole: If either of these tests are normal, the risk of a baby dying within a week of that normal test is very, very, very rare. Okay. Now, as far as how often we do the NST and BPP, if it's just mild growth restriction where the baby's estimated weight is between the fifth and 10th percentile, and it looks like baby is growing normally, and the Dopplers are normal. Then, um, most of the time people will do it once a week. Okay. Some folks don't do NST & BPP is on a regular basis at all for really mild growth restriction. But I think in practice most will do it roughly once a week. Now for pregnancies that are complicated by growth restriction, that is more severe. So less than the fifth percentile where this oligohydramnios where the fluid is low. If you have preeclampsia, if the growth is not staying on track.

Nicole: So for example, if it's the 10th percentile and then we checked three weeks later and it's the eighth percentile, or if there are starting to be abnormal changes in the umbilical artery Doppler studies, then we're going to bump that up to twice per week. Okay. And that can either be two BPPS twice a week. It can be two NST'S, or it can be one NST and one BPP. So it's going to be twice a week testing now for pregnancies that are growth restricted and have very severe abnormalities in the Doppler blood studies. And I'm going to talk about the Doppler velocimetry in just a second, but for pregnancies that have growth restriction and those more severe abnormal changes in the blood flow through the umbilical artery, then you're going to be getting testing daily because those babies can deteriorate very rapidly when we see abnormal changes in the blood flow through the umbilical arteries.

Nicole: Okay. So for the Doppler studies, basically we mostly focus on the blood flow through the umbilical artery. I don't know the rationale behind why we came up with that, but that is what we know is, um, indicative of issues coming up. Okay. So usually Doppler studies are done, um, roughly once a week. So they're done at the same time as the BPP. Okay. So Doppler studies are done once a week and they can fall on the spectrum of no changes. The blood flow to the umbilical artery is fine. They can be sorta in the middle changes where it can be absent and then where there's absent blood flow through the umbilical artery and periods of time. And then something called reversed flow through the umbilical artery is the last thing that we know is a, is a bad sign. So there's sort of mild changes, moderate changes in severe changes in the blood flow through the umbilical artery.

Nicole: And based on that blood flow, we know that as it goes across that spectrum, the baby is more at risk for things like stillbirth. Now, as far as where do we do this monitoring? Most women who have pregnancies that are complicated by growth restriction can maintain their normal activities. And they can usually be monitored as an outpatient. So even though it's a bit of a, can be inconvenience to go to the doctor once a week or twice a week, and have these studies done most of the time, most women can be monitored as an outpatient. There will be a few select group of women who need to be monitored as an inpatient. Those are typically babies that are very severely growth restricted. They need daily monitoring sometimes once or even twice a day. In that case, being in the hospital is just more convenient. And it also allows for prompt intervention in the event that we find something that is a complication where the baby's not moving as much, or if there's evidence on the testing that something is going on, there's not a lot of great evidence that hospitalization improves outcomes.

Nicole: There's also not evidence that bed rest improves outcomes, but it just makes intuitive sense that for babies that are severely growth restricted and at risk, having those moms in the hospital is the best place to be in order to intervene as quickly as possible. The other thing we do if moms have growth restriction is we often do steroids, beta methazone antenatal, corticosteroids, beta methazone is a shot of medication, a steroid medication that can help mature the baby's lungs. Ideally it should be given within a week before a preterm delivery is anticipated. So you may also get steroids if baby is growth restricted, as far as other things to do, there's no evidence that anything else helps. So for healthy women, we don't have anything that we know improves growth and growth, restricted babies. We've tried maternal nutritional supplements, oxygen therapies, interventions to improve blood flow to the placenta, like giving moms more, um, plasma volume to expand their blood flow.

Nicole: We've tried low dose aspirin. We've tried bedrest, we've tried anticoagulation medicine like Lovenox that helps reduce blood clots, but none of those have been shown to help. So we just don't know anything that moms can do in order to improve the growth of babies. Okay. So when will delivery happen for babies that are growth restricted? There's actually not a lot of consensus about the optimum time for delivery. It varies from practice to practice provider, to provider in general, we usually base delivery on how severe the changes are in the Doppler studies through the umbilical artery. And then also some other factors like the fluid around the baby and how the baby looks on the BPP. Okay. Now, if we know that there is reversed flow through the umbilical artery, then those babies tend to get delivered fairly early. If there's something called absent flow, those babies are going to get delivered a little bit later, but still early.

Nicole: And then if the flow is normal than your pregnancy can last a little bit longer. Okay. So roughly in general delivery may happen between 32 to 34 weeks, depending on how severe the abnormalities are in the umbilical artery blood flow. If it's really severe, then it's going to be potentially even earlier. But if we can get you to 32 or 34 weeks, then we, you know, we do our best to do so. Okay. And that's, again, for those more severe changes in the umbilical artery, blood flow, absent or reversed flow, all right, you're going to be 32 to 34 weeks. Now if the blood flow through the umbilical artery is just a little bit decreased, okay. That is not necessarily as good of a predictor of fetal death. And I should say the reason that we're looking at these things is we know that reversed flow through the cord.

Nicole: I'm sorry, through the umbilical artery or absent flow through the umbilical artery. Those are predictive of impending death. Okay. So that's why we get worried about that. So if the blood flow is just decreased, so it's not absent, it's not reversed. If it's just decrease, then we monitor those babies carefully with the continued BPPS and then you're delivered in and BPP is bio-physical profile. Then you get delivered between 34 to 37 weeks. Okay. If the blood flow is just slightly decreased. Also, if we see other signs like the fluid is low, if there's blood pressure issues, if the kidney, if appears to be affected, if the growth has stalled, meaning that the growth was like at the 10th percentile, it was at the 10th percentile. And then now it fell off to the seventh percentile. Then we say, Hey, something's happening. We need to intervene before we have this stillbirth.

Nicole: Or if the weight is really, really small, then we will deliver between 34 to 37 weeks. Now, if the blood flow through the umbilical arterie Doppler study is normal. Then very often we can wait and deliver between 39 and 40 weeks. Okay. Or even, I would say 38 to 40 weeks would be considered reasonable. We don't delay delivery beyond 40 weeks because we know that the risk of fetal death or stillbirth definitely increases beyond 40 weeks, especially the more severe the growth restriction is. So you really don't want to go beyond 40 weeks at the absolute latest. And even then is really just everything is, is looking pretty good and perfect. And in order to get to 38 to 40 weeks. Okay. I hope that didn't sound too terribly confusing. I know was a lot of information, but in general, just to kind of hit back at it.

Nicole: We based it on the umbilical artery blood flow. If there are severe changes in the umbilical artery blood flow, you're going to get delivered earlier. They're sorta in the middle changes and you're going to be in the 34 to 37 week range. If there are no issues in the umbilical artery then the 38 to 40 range. Now, as far as mode of delivery, as long as the testing looks okay, the non-stress test, bio-physical profile or BPP looks okay, then you should definitely go for a vaginal delivery. Even if the cervix is unfavorable. And if there are issues on the non-stress test or the BPP where the baby looks to be in immediate distress, then Cesarean birth is the right thing. But if the baby's heart rate looks okay, everything looks okay, definitely try for a vaginal delivery. There will be an increased risk of Cesarean delivery or increased frequency, I should say, just because there's an increased risk of having a non reassuring, fetal heart rate tracing and a baby that smaller babies that are smaller may suffer from a chronic sort of low level lack of oxygen.

Nicole: And that can be reflected in the baby's heart rate changes during labor, also babies with low fluid. If you have low fluid around your baby, that can increase the risk of abnormal fetal heart rate tracing. So there is a bit of an increased risk of the Cesarean delivery, but again, if everything looks okay, absolutely go for the vaginal birth. And during the course of your labor, we definitely do continuous fetal monitoring, just because of that chronic low level state, potentially of oxygen deprivation. Then we definitely want to keep a close eye on the baby. There's also an increased risk of meconium, a passage of meconium, which has when the baby passes the stool inside. So we definitely want to do continuous monitoring babies that have growth restriction are not great candidates for what's called intermittent monitoring. Also for babies that are 32 weeks or less, we give magnesium because we know that that helps to protect the baby's brain.

Nicole: The final thing that we do for babies at a growth restriction during the course of labor and birth is we have a skilled neonatal team available, especially depending on the size that we estimate the baby will be. And then where you are in the pregnancy. As I mentioned before, growth restriction can be associated with, um, issues with oxygen deprivation. So sometimes babies have a difficult time transitioning to the outside life. When they are affected by growth restriction. Sometimes they have poor temperature regulation, they can have trouble holding their temperature. They have a reduced amount of body fat often, and that can lead to issues with maintaining temperature. Sometimes they have issues with their blood sugar being low. So we definitely want to have a skilled neonatal team available in order to give the baby all of the support that the baby needs. All right. And then the final thing that I want to say is what is the recurrence risk?

Nicole: If you have a small baby in one pregnancy that it's going to be small another time. So roughly the recurrence risk is about 20%. We don't have any good strategies to prevent it. We can address anything that we know is treatable. For example, we know that smoking will increase the risk of growth restriction. So if we can cut back on smoking, then we know that that's something that we can do for women who have really significant known nutritional deficiencies. We can affect that. The other thing that we know may help is, uh, avoiding really short or long periods in between pregnancies. So a short into pregnancy interval would, you know, we want it to be like at least a year before you get pregnant again long would be over two years. Um, so just delaying those intervals may be helpful. The other thing that may be helpful is a low dose aspirin.

Nicole: If the growth restriction was related to preeclampsia. So we know that low dose aspirin helps reduce the risk of preeclampsia in subsequent pregnancies. We don't know anything in terms of dietary changes, supplements, anything like that, that can reduce the risk bed, rest, nothing like that, that doesn't work. Okay. I know that was a lot of information. So just to recap, growth restriction is when the baby's growth on ultrasound is estimated to be in the less than 10th percentile. We typically screen for it by measuring the fundal height and then do select ultrasound. If we see that there's a discrepancy, some folks go straight to ultrasound based on having a higher risk of known growth restriction, or we can't measure the fundal height. So if you have extra weight around your belly and we can't feel your uterus, or if you have fibroids distorting the size of your uterus, or if you have diabetes before pregnancy hypertension, before pregnancy things that we know predispose you to growth restriction, then we go ahead and go straight to ultrasound.

Nicole: Otherwise we screen with just the fundal height. When we diagnose fetal growth restriction, then we monitor the baby by monitoring the baby's growth, monitoring how the baby is acting inside in the uterine environment. And then finally, the blood flow studies with Doppler studies, particularly through the umbilical artery, we deliver based primarily on how those Doppler blood studies are. If they're severe changes, you're going to get delivered earlier 32, 34 weeks, or even earlier in some severe cases, if they're just mild changes between 34 and 37 weeks, if there are no abnormalities in the Doppler studies and 38 to 40 weeks, and definitely not later than 40 weeks because of the increased risk of stillbirth. And then finally during the labor and birth, which you can definitely go for a vaginal delivery, we want to monitor the baby it continuously and also have a skilled neonatal team available just in case.

Nicole: Ooh, y'all, I feel like a, got a little bit tongue tied on my words in this episode. Now that is it for this episode of the podcast. I know that that was a lot of information and I hope it was not too overwhelming for you. And you definitely have a bit of a better understanding of the things that we look for with growth restriction. Again, it's important to be prepared just in case and not feel so scared and overwhelmed when those things happen. Now if you have more questions, if you want to know of other women have experienced something similar and what they've gone through, definitely hop on into my free Facebook group. It's called all about pregnancy and birth. That's a great group to ask questions after the show to connect with other pregnant mamas. It's a really, really supportive community. It's run by my community manager, Kesha.

Nicole: Who's an experienced doula. And of course I pop into the group as well, but really the best part of the group is the other pregnant mamas in the group. So do check that out. It's on Facebook group, it's called All About Pregnancy and Birth. Also be sure to subscribe to the podcast and Apple podcast or wherever you listen to podcasts. And I would love it. If you leave a review in Apple podcast, it helps other women to find the show. I do shout outs from those reviews and it just really helps show to grow. So I so

Nicole: Appreciate them when you take the time to do that. I just love hearing what you think about the show. Now, next week on the podcast, it will be a birth story episode so do come on back next week. And until then, I wish you a beautiful pregnancy and birth. Thanks so much for listening to this episode of the all about pregnancy and birth podcast, head to my website and see our coaching.com to get even more great info, including free downloadable resources on how to manage pain and labor and warning signs to look out for after birth. You'll also find information on my free online class, on how to make a birth plan, as well as everything you need to know about the birth preparation course. Again, that's NCRcoaching.com and I will see you next week.