Ep 251: Low Amniotic Fluid? High Amniotic Fluid? What Do Amniotic Fluid Levels Mean for Your Baby?

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Amniotic fluid (AF) is the liquid that surrounds your baby after the first few weeks of pregnancy. An adequate amount of amniotic fluid is absolutely, positively critical for fetal health. If it’s too low, there can be a risk of severe fetal deformations, umbilical cord compression, and in extreme cases, fetal death. On the other side, if it’s too high, there’s a range of other fetal disorders that can occur affecting both you and your baby. Neither extreme is very common, but they both require monitoring and special care.

In this Episode, You’ll Learn About:

  • What the purpose of amniotic fluid is
  • What it is made up of
  • Where it comes from
  • How it is measured
  • How low and high AF can affect development

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Dr. Nicole (00:00): What exactly is amniotic fluid? What does it mean for your baby? If your amniotic fluid is too low? What does it mean for your baby? If your amniotic fluid is too high, you are going to learn all about it in this episode.

(00:20): Welcome to the All about pregnancy and birth podcast. If you're having a baby in the hospital, you are giving birth in a system that too often takes away power from women over what happens in their own bodies. I'm Dr. Nicole Calloway Rankins, a practicing board certified OBGYN, who's had the privilege of helping well over a thousand babies into this world. I've been a doctor for over 20 years, and I'm here to help you take back your power, advocate for yourself, and have the beautiful pregnancy and birth that you deserve. This podcast is for educational purposes only, and it's not a substitute for medical advice. Check out the full disclaimer at drnicolerankins.com/disclaimer. Now, let's get to it. Hello there. Welcome to another episode of the podcast. This is episode number 251. Whether it's your first time listening or you haven't listened before, I'm so glad you're spending some time with me today.

(01:14): In this episode, you're going to learn all about amniotic fluid. What is amniotic fluid? What's in amniotic fluid? Where does amniotic fluid come from? How do we measure amniotic fluid? What does it mean when your amniotic fluid is too low and what does it mean if it's too high? We're covering all of it today. Now, before we get into the episode, I want to do a quick listener shout out. This is from C-L-O-U-I 87. They left me this review in Apple Podcast and it says, thank you for episode 104. Recently I realized that I needed to own my pregnancy trauma stories, high risk pregnancy, relationship, hurt, preterm delivery, two month NICU stay missed miscarriage as what they were traumatic. I went searching for podcast to start getting encouragement in my ears. This episode was validating, encouraging and challenging exactly what I needed to start using resources and get more support.

(02:21): Thank you. Well, thank you so much for leaving that review about how impactful that episode was for you. Now, if you also find this podcast impactful in your pregnancy and your birth, I would so, so appreciate it. If you head on over to Apple Podcast and leave me a review. If you really love the podcast, I'd appreciate a five star review, but I really just want you to be honest and tell me what you think about the show. I love to hear what you think, and I also do listeners shout outs from those reviews. So head on over to Apple Podcast. Let me know what you think about all about pregnancy and birth. Okay, let's get into this conversation about amniotic fluids. So first off, what is amniotic fluid? Well, amniotic fluid is the liquid that surrounds your baby after the first few weeks of pregnancy, and it has a number of critical functions that are absolutely essential for normal growth and development of your baby.

(03:18): Amniotic fluid cushions, the umbilical cord from getting compressed or squeezed. Amniotic fluid has antibacterial properties that provide some protection from infection. It actually serves as a reservoir of fluid and nutrients for your baby. It also provides the necessary fluid space and growth factors to permit normal development of your baby's lungs, musculoskeletal system, and gastrointestinal system. And finally, amniotic fluid helps protect your baby. It just cushions your baby from any trauma if your belly is accidentally hit. Now, what is an amniotic fluid? Well, amniotic fluid is about 98 to 99% water and then one to 2% solids, which includes proteins, carbohydrates, electrolytes, fats, enzymes, hormones, and amniotic fluid also contains a variety of types of fetal cells. So there are skin fetal cells, respiratory fetal cells, intestinal fetal cells, urinary tract fetal cells, stem cells. There's also hair, blood cells, cells that are shed from the amnion, and then sometimes amniotic fluid can get stained with meconium, which is essentially baby poop.

(04:42): So where does amniotic fluid come from? We're early in the pregnancy. Amniotic fluid is likely derived from the surface of the placenta, partially from secretions from the surface of the body of the embryo, and then what's called a trans membranous pathway, which is like transport from the maternal compartment across the Amon. That's a fancy way of saying that fluid kind of comes through the placenta essentially. And then as the pregnancy progresses, the vast majority of amniotic fluid comes from where your baby making urine. Yes, y'all. We all grew up in a pool of urine, our own urine inside our mother's bellies. So it's estimated that especially towards the end of pregnancy, your baby will make anywhere from 800 to 1200 milliliters a day of urine. Okay, 800 to 1200 milliliters a day, a day of urine, that's about half of a two liter bottle every single day that your baby makes.

(05:51): Now, if your baby is making that much urine every day, then how does the fluid levels stay constant? Because the amniotic fluid volume actually does not change significantly from day to day. The overall volume stays about the same. And the reason that that happens is not only is your baby making 800 to 1200 milliliters a day, your baby is also swallowing about that same amount a day, a little less, anywhere from 500 to a thousand milliliters per day. So the amniotic fluid volume, again, doesn't change significantly from day to day, but the amniotic fluid itself is generally completely replaced over 24 hours. So every day your baby makes some swallow, some make some swallow some every single day. Now, how do we measure amniotic fluid? Ultrasound examination is the only way that we can assess amniotic fluid volume, and there are two ways that we do that.

(06:55): One is qualitative and that's when we just kind of look at the fluid on ultrasound and subjectively say, oh, the fluid looks low, the fluid looks normal, or the fluid looks high. This is actually surprisingly very accurate if it's an experienced person who's looking at the amniotic fluid, and I can say in my experience, you can look and you say, oh, that looks about normal, that looks about low. Oh, that maybe looks a little bit high. So that's actually pretty accurate. And then the other two methods are quantitative and where we actually measure something. And what we're doing is we're trying to take a 3D picture or a 3D object, the amniotic fluid and return it into a 2D or a two dimensional measurement. So there are a couple of ways that we can do this. One is called the single deepest pocket. It's also called the maximum vertical pocket or the largest vertical pocket, and it's the vertical dimension and centimeters of the largest pocket of amniotic fluid that does not have any umbilical cord going through it.

(08:02): So it's really on the screen just going to look like a whole lot of black amniotic fluid looks just dark on the screen and the largest pocket can't have any cord in it. It can't have any arms or legs, any fetal extremities in it. And it's supposed to be measured at a right angle to the uterus, not that that's something that you would know. And the way that we quantify whether the fluid is low, normal or high is how deep that pocket is. So if the depth is less than two centimeters, then fluid is low and low fluid is called oligohydramnios. Oligo means low and hydro is fluid. A normal single deepest pocket or maximum vertical pocket is going to be greater than or equal to two centimeters and less than eight centimeters. That's normal. And poly hydros, poly meaning many hydros is fluid. A depth greater than or equal to eight centimeters is polyhydramnios.

(08:59): Now the other way that we measure amniotic fluid is something called the amniotic fluid index, and that's calculated by dividing the uterus into four quadrants using the linea nigra. That's the line that runs down the middle of your belly button. So we use that line and on everybody, it looks different. Some people, it's really prominent. It tends to be more prominent during pregnancy because of the hormonal changes. So we use that line to divide the right and left sides of the uterus and then across theus or the belly button, and then that does the upper and lower quadrants. So we do the line nigra up and down, and then align across the belly button to make four quadrants. And then we measure the maximum fluid pocket in each quadrant. That doesn't contain cord, doesn't contain any extremities. Again, it's going to look dark or black. Ultrasound is echogenic. It looks black on ultrasound, and we measure that in centimeters. And the sum of the measurements in each of those four quadrants is the amniotic fluid index. So if the amniotic fluid index is less than or equal to five centimeters, if it's greater than five and less than 24 centimeters, then that is normal. And if the a FI is greater than or equal to 24.

(10:25): So let's talk about what it means when you have oligohydramnios and when you have poly hydro. So oligohydramnios again is when the fluid is low, it's lower than expected for the gestational age of pregnancy. So it's that depth of less than two centimeters for the single deepest pocket, or it's an amniotic fluid index. The overall index is less than five. An adequate amount of amniotic fluid is absolutely positively critical to normal fetal movement. It's critical to normal growth for your baby. It's critical to cushion the baby in the umbilical cord. So when the fluid is low, these processes may not happen, and that can lead to potentially really severe fetal deformation where the limbs don't form like they should. It can lead to umbilical cordic compression, and in extreme cases, it can lead to fetal death. Now, what causes low amniotic fluid really depends on the trimester.

(11:34): So in the first trimester, the baby's tiny. There's not really a lot of amniotic fluid. Period is really not common to say there's low fluid in the first trimester. It's just not something that's very often seen. Now, if in the second trimester we see low amniotic fluid, that is very concerning because that's when the baby really begins to make urine. So if the fluid is low in the second trimester, then we're very concerned that there's a problem with the baby's kidneys, with the baby's ureters, which are the tubes that run between the kidneys and the bladder? Is there a problem with the bladder? Is there a problem with the urethra which gets urine from the bladder to the outside of the body? So we need to know, or there's a possibility or there's a concern that something is wrong in that system where urine is not being made at all because maybe there's no kidney or there's something wrong with the kidneys or the urine can't get out.

(12:33): Those issues will account for about 50% of low fluid in the second trimester, another 35% of low fluid in the second trimester, and that's 14 to 28 weeks. That will be caused by Ppro M something which is P-P-R-O-M, preterm premature rupture of membranes, which is your water breaks before term, so before 37 weeks. And it's premature, meaning it's before labor starts. So prom accounts for about 35% of low fluid in the second trimester. Now in the third trimester prom accounts for most of low fluid or some sort of uteroplacental insufficiency, meaning the placenta is not working great, the baby is not getting the nutrients that it needs, and it demonstrates that or is conserves energy by holding onto fluid, holding onto urine and not actually making urine or making amniotic fluid in conditions where we can see this show up, our preeclampsia are high blood or just high blood pressure or diabetes potentially.

(13:46): And often if it's low fluid in the third trimester, it's frequently accompanied by the baby not growing as well, so the baby doesn't have all of the nutrients and things that it needs in order to thrive. And then actually another common cause of low fluid, especially in the summer months, is dehydration. If you are dehydrated and then your baby's not getting enough fluid, then it can actually cause the fluid to be low. And I'll talk about some of the treatments in just a minute. Actually, there's really not much treatments. There are no treatments that have been proven to be particularly effective for low fluid. If we suspect that you're dehydrated, then we do do maternal hydration through IV fluids or just have you drink lots and then we'll recheck the fluid in a day or so to kind of see where things are. But really there's no treatments that have been proven to be effective in the term.

(14:41): And the reason that we suspect when the fluid is low, it may be that the baby is measuring smaller than expected or your uterus is measuring smaller than expected, or obviously you say that you're leaking fluid, then we're going to be concerned and make sure that the fluid level is okay. It's not infrequently found on an ultrasound that's done for something else, for someone who's at risk, for someone who's getting regular ultrasounds. So for example, for someone who has diabetes or someone who has hypertension in pregnancy and they're getting regular ultrasounds, that is when we may pick up low fluid. Most of the time it's found in the third trimester, so that's after 28 weeks. And we can't always necessarily identify what the exact cause is. We know that it's associated with other things, like I said, like diabetes or hypertension, things like that. But it's not always easy to pinpoint the exact cause.

(15:33): Now, the prognosis for low amniotic fluid really depends on when it was diagnosed. So low fluid in the first trimester. Unfortunately, that is a very bad sign. If the fluid looks low in the first trimester, 95% of those pregnancies will end in miscarriage. So that's a really bad sign. And the second trimester, if the fluid is borderline low, then pregnancies tend to go on to be normal. So it looks like it's just right on the border being low, that tends to be okay. However, if the fluid is actually truly low between 13 and 24 weeks, that is also unfortunately a bad sign. Only about 20% of those babies will survive. And of those that do survive, the babies may have anatomical and functional abnormalities like skeletal deformation or contracture, and their lungs are not as developed as something called pulmonary hypoplasia. And that's a result of developing in a severely low amniotic fluid environment.

(16:40): That fluid is important to help the limbs move and help the baby to be flexible and move its arms, legs, and things around. When the fluid is low, essentially the baby is squeezed and things just can't develop properly. Now in the third trimester, the prognosis really depends. The earlier in the third trimester, low fluid is diagnosed than the worst. The outcomes. If amniotic fluid or low amniotic fluid is diagnosed towards the end of pregnancy, generally the outcomes are very, very, very, very good. So what do we do during pregnancy? If low fluid is diagnosed? Well, it really depends on what the underlying condition is, so I don't want to go into that in detail. But in general, it just means we are going to do some closer monitoring, closer, closer monitoring, watch the fluid, watch the levels. We'll look at other things like how is the baby growing?

(17:37): We'll look at the blood flow through the placenta, we'll look at the blood flow through the umbilical cord and just keep a close eye on the baby. Very often. If the fluid stays persistently low, then I shouldn't say very often. Like always, we're going to recommend induction and early delivery, especially as you get closer to 37 weeks or even sooner, sometimes 36 weeks because we believe that the baby's going to be better on the outside and the environment that we can provide on the outside and support that we can provide on the outside than what the baby is getting on the inside. So typically, we watch very closely, and we may deliver as early as 37 weeks, maybe even a little bit sooner if the fluid remains persistently low. So on the flip side is polyhydramnios. Polyhydramnios is when you have excessive amniotic fluid. I actually had that in both of my pregnancies, mildly in the second one, a lot in the first one.

(18:38): And I'll tell you why in just a minute. So this diagnosis is also made by ultrasound examination, and it's a depth that maximum vertical pocket of greater than or equal to eight centimeters or the overall fluid volume is greater than or equal to 24 centimeters. The A FI, and it happens in about one to 2% of pregnancies. Now the causes, and you can kind of divide them into two big categories. One is increased fetal urine, and the second one is decreased fetal swallowing. Now, the most common causes are fetal structural anomalies, and that is the case. What happened with my first daughter, she had something called duodenal atresia where the first part of her intestines were not connected. It's a condition that happens in about one in 7,000 to one in 10,000 pregnancies. And when the first part of the intestines aren't connected, when she swallows, the fluid isn't going anywhere.

(19:47): The most that it could go is the stomach. So it was basically coming backing up in a sense, and she couldn't swallow. And so she had a lot of extra fluid, tons of extra fluid. She was in there flipping and dancing and all kinds of things, so that's why she had extra fluid or I had polyhydramnios with that pregnancy. And then other causes of polyhydramnios are chromosome abnormalities like trisomy 18, which is an extra chromosome number 18. Also, if there are any cardiac problems, and it's something called a high fetal cardiac output state, and basically the baby's heart is pumping out a lot and it causes anemia that can lead to polyhydramnios, twin transfusion, transfusion syndrome can lead to polyhydramnios where one baby is basically siphoning from the other. There are some rare viruses infections like parvovirus that lead to polyhydramnios. Actually, if mom has diabetes that can be associated with polyhydramnios.

(20:54): We're not exactly sure why. And then sometimes even as many as 30 to 40% of cases of polyhydramnios or what we call idiopathic, meaning we don't know what causes it. So that's what I had with my second daughter. There was no identifiable reason for why I had extra amniotic fluid with her, but she had extra amniotic fluid and there were no other reasons. So when you look at the big picture, about a third are associated with the congenital anomaly. A quarter are associated with diabetes, and the remaining 40% are considered idiopathic. Now, when we look at or when we suspect polyhydramnios is when the uterus is bigger than we would expect. For me, I was, especially with my first daughter, when I had lots of extra fluid, I was just huge. People kept thinking, asking me, do I have twins? Or how far along are you? So the uterus is going to be larger than expected for how far along you are in the pregnancy. That's usually the first time where we check and see, is it the baby that's too big or is it the fluid That's too much, and it may also be detected when we're looking for other things. So if you have hypertension or diabetes, then we may see it then.

(22:15): Most of the time the increase in fluid is asymptomatic. You don't necessarily notice it if you have increased fluid, but if it's a lot, then you can experience some shortness of breath, especially as you get further along in the pregnancy. And you can also experience contractions. You can have more frequent kind of irritable contractions. They're not labor contractions, but they are contractions. It's like an irritant to the uterus to have all of that fluid there, and it can just feel uncomfortable. You just feel kind of big and sort of miserable. Now, what does it mean for your pregnancy if there is extra amniotic fluid? Well, most cases of idiopathic polyhydramnios, meaning we can't identify a cause, they generally resolve spontaneously, especially if it's mild. But sometimes polyhydramnios can be associated with an increased risk of several outcomes in addition to some poor outcomes related to some what's called morphologic abnormalities.

(23:17): So it can cause maternal respiratory compromise, meaning mom just has a hard time breathing. It can increase the chances of preterm labor or preterm rupture of membranes or preterm delivery. I actually went into labor with my first one early at 32 weeks. Did it have to do with the extra amniotic fluid? Maybe it can definitely lead to fetal malposition where the baby is not head down, essentially because the baby has of room to flip and change and swim in there. It increases the risk of something called umbilical cord prolapse, where once the water breaks and the umbilical cord comes first through the vagina ahead of the baby, that is a true, true emergency. We have to rush back immediately for a c-section. When that happens, it can lead to an increased risk of placental abruption when the membranes rupture, because when all that water comes out and the uterus kind of shrinks down a little bit or a lot of it potentially, and the placenta can shear away from the wall of the uterus, that rarely happens, but it's a possibility.

(24:23): And then also sometimes the uterus just gets a little bit lazy after birth. If it's been big and full of fluid, it doesn't want to shrink down. We'd like that can lead to what's called uterine a acne, and that can increase the chances of postpartum hemorrhage. Now, as far as management, it really depends on the gestational age as well as the presence of symptoms and the cause. Extra testing is not necessarily needed or standard in extra amniotic fluid like it is an low fluid. So in mild to moderate extra fluid, then typically you may do a non-stress test every one to two weeks until delivery, and then maybe weekly after that. So it's not necessarily a ton of extra monitoring. And then in very extreme instances, we will reduce the amount of amniotic fluid. That's called amnio reduction. And essentially what it is is like I had this done to try and stop my preterm labor, is they stick a needle in your belly through your uterus and drain off the amniotic fluid.

(25:35): I know it sounds crazy. It's actually not that painful because the needle's pretty small, but it's just to decompress some of the fluid, and it's really only indicated for severe maternal discomfort or shortness of breath in the setting of really bad poly hydros. In my case, they thought maybe it might help slow things down. With my labor. It did not. And then in mild to moderate polyhydramnios and all of the testing looks normal, we typically don't necessarily need to induce labor early, maybe at 39 to 40 weeks. As long as everything looks okay, we don't want to go too far past 40 weeks because the risk of fetal death does seem to increase after that. But unlike oligohydramnios, where we tend to induce a little bit earlier, we can go a bit longer with polyhydramnios. And then the last thing is that during labor, we just have to be really careful about monitoring the baby because with all of that fluid, babies can move around.

(26:33): They can flip from head down to breach and have to be careful about breaking your water. Sometimes we wait until we break the water, until we know the head is really nice and well applied to the cervix. So we don't have that umbilical cord prolapse because that is truly, truly one of the obstetric emergencies where we run to the or rip the cords out of the wall. So we have to be careful about artificially breaking your water and doing that under safe, safe circumstances, or if it ruptures on its own, just making sure that that doesn't happen or placenta abruption doesn't happen. But most of the time, the extra amniotic fluid doesn't end up being a problem. I very, very rarely see these things happen with people that have extra amniotic fluid. Okay, so just to recap, amniotic fluid is the fluid that surrounds your baby.

(27:23): It has a number of important functions. It cushions the cord. It's essential for normal growth and development has some antibacterial properties. It primarily comes from your baby making urine. It gets regenerated every day. Your baby makes the urine, swallows the urine, makes the urine swallows the urine. We measure it by ultrasound. That's the only way we can measure amniotic fluid. And we do it either by the single deepest pocket or the overall amniotic fluid index. And when it's low, it can have some significant issues. For a baby when it's high, it can also have some problems for a baby. Neither extreme is very common, but they both require monitoring and special care depending on the cost to make sure that you and your baby are safe. Alright, so there you have it. Please subscribe to the podcast and Apple Podcast. And while you are there, leave me that review and Apple Podcast. I was so, so, so appreciated. So I can do a shout out for you in an upcoming episode. Also, come follow me on Instagram where I have more great pregnancy and birth information there. I'm on Instagram at @DrNicoleRankins. So that's it for this episode. Do come on back next week and remember that you deserve a beautiful pregnancy and birth.