Mailbag 36: “What does the Fox say” – With Dr. Nathan Fox

Welcome to today’s episode of “Healthful Woman,” a podcast designed to explore topics in women’s health at all stages of life. I am your host, Dr. Nathan Fox, an OBGYN and maternal fetal medicine specialist practicing in New York City. At “Healthful Woman,” I speak with leaders in the field to help you learn more about women’s health, pregnancy, and wellness.

Hey, everyone. Welcome to our “Mailbag Podcast Number 36 What Does the Fox Say?” Our first question is from Kim. “Hi, Dr. Fox. I continuously listen to your podcast after being featured as one of your high-risk birth stories on cord prolapse. I just had my second baby via planned repeat C-section. After the delivery, my OB told me I had a thin lower uterine segment with visible amniotic sac, likely in the setting of uterine dehiscence. I was wondering if you could speak a little about uterine dehiscence. How common is it? Could it affect uterine healing after delivery? Is it risky to have another pregnancy after prior uterine dehiscence? Thank you so much, and I look forward to hearing your thoughts on this topic.”

All right. Kim, first of all, thank you for the question. Second of all, thank you for listening. Third, so nice to have you back on the podcast after telling your birth story. Great to hear from you. Thank you so much. Okay. In terms of your question, I’m going to answer it, but I’ll start with a little preview. First, on uterine rupture, A, so I can explain how it’s different from what you had, and B, because our next question is going to be about uterine rupture.

All right. So, I think, as many of our listeners know, uterine rupture is a situation where usually in labor — in theory, could happen not in labor, but typically in labor — when the uterus is contracting, the uterus actually opens up on the inside of a woman’s body. And it can be very dangerous for her, for the baby, not necessarily if we catch it in time, but it could be. And it’s more common in women who’ve had an incision on their uterus prior, like surgery on the uterus prior, which is most commonly a prior C-section, though it could be other surgeries like myomectomy, removal of a fibroid, or whatnot.

And because of this risk of uterine rupture, when someone is trying to decide, should I try for a VBAC, should I not try for a VBAC, meaning a vaginal birth after a caesarean, part of the conversation is, all right, if you try, there is a risk of when you’re laboring of that scar from your C-section opening up inside. We call it uterine rupture. Again, we say it could be dangerous for you, it could be dangerous for the baby, what is the chance it will happen?

Typically, it’s about 1%, but based on the circumstances, it could be higher, it could be lower, but that’s sort of the conversation, and that’s uterine rupture. But it’s a clinical situation where someone’s in labor, and if the uterus ruptures, typically, we see the baby’s heart rate drop, we see, you know, often the woman starts bleeding. Maybe when we do an exam, the head seems higher up again, depends on the circumstances, but those are possible things. And that’s a clinical situation, and that’s what happens.

Okay. There is a situation that can happen prior to that, which is not a uterine rupture, where the muscle of the uterus separates, but it’s not completely separated. I mean, there’s still a very thin layer of uterus holding on over that scar, that could be the…what we call the serosa, which is sort of like a saran-wrap-like outermost layer of the uterus, or sometimes it’s the amniotic sac itself. Both of those look like a piece of saran wrap. You could sort of see right through them.

And so, in that situation, which we’ll usually find at the time of a C-section, we’re doing the C-section, when we look down at the uterus, instead of just seeing sort of pink or red thick muscle of the uterus, we actually see on the bottom part where that scar was, it looks literally like a window, where there’s a section where all you see is this like paper thin membrane, which is see-through. And through it, you can see the baby, you can see fluid. You know, whatever’s there is what you can see. And so, we sometimes call that the uterine window. We sometimes call that a uterine dehiscence. We sometimes call that a thin lower segment. Exactly why you would call it one versus the other, sometimes depends on just semantics, sometimes it actually depends, and different people do it a little bit differently.

So, there are different ways that people sort of describe this, but conceptually, Kim, it sounds to me that what your doctor was describing was a situation where, you know, you had a planned repeat C-section. So, you’re not in labor. They’re doing the operation, they go and they look down your uterus, and it looks like the muscle of the uterus separated, but not completely, such that they could sort of see through the last layer and see into the uterus. And they call it a thin lower segment with visible amniotic sac. They call it a uterine dehiscence, some people call it a uterine window. So, that’s what happened.

And in terms of your questions, how common is it, could it affect healing, is it risky, all these things, well, in terms of how common it is, it is more common the more C-sections you’ve had. It’s more common if you’ve had one before. The actual incidence of it is not entirely known, and different people report different rates. This is actually something we’re in the midst of studying and probably publishing. So, maybe by the time this podcast has dropped or maybe within a year or so afterwards, if you PubMed or Google or whatever scholarly articles, you may find an article by our group on this. We published on it before. And in some women, it could be as high as a 10% chance of this happening. Again, this is typically in people who’ve had multiple prior C-sections. So, that’s sort of the incidence of it.

Now, the question is how important is it or how scary is it or how risky is it? It’s not really known. The thought is that it’s risky. The thought is that if you have this situation and it’s very, very thin, and you don’t have a lot of uterus left and you go into labor, you would think that maybe you are at a higher risk of having a uterine rupture compared to someone who has a thick muscle on the uterus. That is sort of a thought that we have. It makes a lot of sense. It’s hard to sort of prove it scientifically because you would have to know who has a window and who doesn’t have a window before they go into labor to know what the chances are of uterine rupture in the group that has a window and a group that doesn’t have the window. So, that’s hard to do. There have been studies that look with ultrasound to measure how thick the uterus seems to be during pregnancy, ultrasound and see if that changes the risk of a rupture. It might, but most of the data is not so clear that the thickness on ultrasound really matters.

And so, it’s one of these things where, when we see it, we’re happy that we didn’t have our labor, but we don’t really know what would have happened if she went into labor. Presumably, there are some women who have a window who go into labor and don’t have a uterine rupture, but it’s hard to say exactly what those rates are. So, for us, if I know someone has a window or if they had a window in the past, we usually treat them similar to someone who’s had a history of a uterine rupture. And namely, we try to deliver them, A, by C-section and, B, before they would go into labor.

So, exactly when that is depends, but let’s say somewhere around 36, 37, 38 weeks, somewhere in that range. Meaning, prior to their due date, prior to 39 weeks, we usually deliver them a little bit earlier. And again, the exact how early depends on some of the specifics of the situation. But conceptually, in our practice, we treat them similar, not exactly the same, but similar to women who’ve actually had a prior uterine rupture that we really prefer they have a C-section the next pregnancy and not go into labor.

So, for you Kim, for future pregnancies, I would recommend having a C-section. And again, without knowing the details and without being into operation, assuming it’s what I think it was, I would normally say, all right, you should probably have your C-section early. So, sometime around 36, 37 weeks, again, in that range rather than doing it at 39 to 40 weeks, which is when you would typically recommend another scheduled C-section. So, that’s sort of what the ramifications are of it.

Now, does it affect uterine healing after delivery? Not really. I mean, because you can still sew the uterus together and this or that, but it does put you at increased risk for having another window or something. And so, sometimes what we’ll recommend is, after the C-section where you see the window, in between pregnancies, we do a test called the saline sonohysterogram, where we put water in the uterus and look and measure the thickness of the uterus around where the scar was to see how well it healed. And then sometimes we make decisions about what to do about that in the next pregnancy or before the next pregnancy.

So, it’s a complex topic, and it has to be very, very individualized. But conceptually, a window is where the uterus separates, but it’s not a clinical uterine rupture. It’s usually noted at the time of a scheduled cesarean or a cesarean in labor, but again, without symptoms of a rupture. It doesn’t impact the baby right there at that time because we just opened up the uterus to deliver the baby, but it does put you at increased risk in future pregnancies of it happening again, potentially risk of uterine rupture. So, we typically might do some evaluation between pregnancies, and then in the next pregnancy typically recommend delivery by cesarean and earlier than one would normally do it for a repeat C-section.

Okay. Next question, related topic from Jessica. “Hi, Dr. Fox. I love your podcast.” Thanks, Jessica. “I’d love to get your opinion on my situation. My first pregnancy ended in spontaneous labor at 26 weeks, and my son was born via C-section. He tragically passed away three weeks later in the NICU. I was lucky enough to get pregnant five months postpartum, and had a relatively easy pregnancy with a plan to deliver via C-section at 37 weeks. I went into spontaneous labor at 36 weeks and 3 days, and unfortunately had a complete uterine rupture along my prior C-section scar with extension to the left. Thankfully, both myself and my daughter were okay, although slightly traumatized. I was connected with an extremely well-regarded surgeon here in Canada. And he did a laparoscopic repair of my defect at 14 months postpartum, and has since cleared me to carry another pregnancy. I was not sure this would be the case. My question for you is, what is my risk of having another preterm birth, and how do you feel about carrying after rupture? Any insight would be greatly appreciated.”

Okay. First of all, Jessica, thank you so much for sending in the question. Thank you for sending in the question and sharing what happened to you and your first pregnancy and your son that passed away. I know it’s probably difficult to have it read out loud and heard by others, but I really do appreciate you letting us know about that and be willing to share that with us. I’m also very happy that your second pregnancy went well, and you and your daughter are well despite having another pretty eventful delivery with the uterine rupture.

Okay. So, carrying over from our last question and into yours. So, starting with the uterine rupture. So, you had a history of a C-section at 26 weeks. You were planned to deliver at 37 weeks, and I think that makes a lot of sense. And you did not include this in your question, but just for our listeners, my guess is the reason the C-section was planned at 37 weeks in your second pregnancy and not at 38 or 39 weeks is either because your son passed away, and therefore, there’s a lot of increased anxiety about sort of continuing pregnancy and waiting. It’s usually, or often, when someone is full term, we’ll just recommend delivery around that time, 37 weeks or/and — it could be both — when we do C-sections that early at around 26 weeks, sometimes the incision we have to make on the uterus is different than the one we typically do.

And then those different type of incisions, sometimes they’re what we call classical or vertical or higher up on the uterus, there is a much higher risk of uterine rupture. And so, we prefer to do the second C-section, the repeat C-section prior to going into labor because we’re concerned about uterine rupture. So, it could have been either of those reasons. But ultimately, when you were scheduled at 37 weeks, you went into labor a few days prior, and you did have the uterine rupture along the prior C-section scar. So, again, that’s sort of a clinical situation where presumably they noted that the heart rate was dropping, you were bleeding or whatever it was, and they did the emergency C-section.

And as I said at the last question, thankfully, even in the setting of a uterine rupture, if it’s seen in time and you can do a repeat C-section quickly, the mother and the baby are most commonly okay. Again, not always, which is why it’s so scary, but they can be, and in your case, thank God they were. But that is sort of the uterine rupture situation. I imagine there’s a possibility that had you not gone into labor at 36 weeks and 3 days and they did your C-section at 37 weeks, maybe that’d be a situation where they would have seen a window. I don’t know. Obviously, it’s hard to say that for sure, but that’s a possibility.

So, it sounds like, based on what you’re saying in your question, that after your daughter was born and after you recovered from the C-section, they did some sort of evaluation, like I was talking about in the last question, to look at how this scar healed. And obviously, they thought it didn’t heal perfectly because they recommended a laparoscopic repair to fix that scar, and you had that. And they seem to be comfortable that it’s okay now and that you could have another pregnancy. And so, your questions to me were, number one, what’s the chance of having a preterm birth again? And the second is about…is whether I think it’s safe for you to get pregnant or not.

So, in terms of the chance of a preterm birth, hard to say. It depends on sort of why you had the preterm birth. I would need to know more details about that. In general, people of a preterm birth have an increased risk of it happening again. Now, it doesn’t mean 100%, but there is an increased risk, you know, ballpark 20% to 50%. I think, for you, most likely, in your next pregnancy, they’re not going to deliver you at 37 weeks, but rather closer to 36 weeks. So, if they deliver you at 36 weeks and you were going to go into labor at the same time, 36 and a half weeks, you will have been delivered before that happens. So, it shouldn’t be an issue. But I do think that there is an increased chance of having a delivery even before 36 weeks compared to somebody else. And that would need to be monitored closely, maybe go on progesterone. Again, depends on the exact circumstances. But I do think that it is appropriate to have that concern about preterm birth and to be cognizant of it and to be watched closely for it. Exactly what to do about it will depend on the circumstances.

In terms of how safe it would be, you know, traditionally, if women had a uterine rupture, they were told, never get pregnant again. It’s too dangerous. You have a high risk of having a rupture again, and it’s not safe for you. It’s not safe for the baby. And that was sort of the tenet. And then over time, people just did get pregnant after a history of a uterine rupture, either because maybe their doctor didn’t tell them that recommendation or because maybe their doctor did, but they got pregnant anyways. And ultimately, there were women who were pregnant with a history of uterine rupture. And assuming that they were followed closely and delivered early, before going into labor again, so maybe 36 weeks or 37 weeks, something like that, many of them did well. And people saw that, and then more people did it and sort of it became more of a thing to have pregnancies after uterine rupture.

I can say, in our own practice, this is something we see a lot of. We published on it, I want to say, I think two studies on this, looking at our experience in women with a history of uterine rupture or history of the uterine window, and sort of what did we do and what did we find. In general, our experience has been that the vast majority of women with a history of a uterine rupture will have safe and uncomplicated pregnancies, again, assuming you do the right evaluation and follow them closely, deliver them early by C-section, all of those things. Again, nothing’s a guarantee, but in our experience, they tend to have good outcomes.

So, in general, obviously, Jessica, you don’t look to a podcast to get cleared whether it’s safe to have pregnancy. You’re just asking me a question about my opinion in general. And so, in general, for women who have a history of uterine rupture, I would say, having another pregnancy and delivery is not off the table, but it does require a thorough conversation, evaluation, sometimes imaging like the saline sonohysterogram. And then in pregnancy, close monitoring, early delivery, C-section, all of those things. And assuming everything sort of checks out and is okay, usually, the outcomes are good, and you’ll have an uncomplicated repeat C-section.

Now, whether the procedure you had to evaluate and fix the scar makes your situation better or the same is very hard to study. I think we recently did a podcast on this or it was a “Mailbag” question on this, where it’s a thing that’s done, hard to prove one way or another that it’s a good thing to do or not a good thing to do or a neutral thing to do, but there is a lot of common sense to this that if the scar really looks like it’s not healed well, you may want to fix that before someone gets pregnant again. So, I do think that, assuming they did a good job, which I assume they did, and it looks…the uterus and the scar looks well-healed afterwards, that I would say, my best guess is it probably made your risk a little bit lower. And so, it would make your doctors probably a little bit more comfortable with you getting pregnant again. Best of luck with the future pregnancy. And hopefully, they’ll watch you very closely, deliver you early, and things should go very well.

Okay. We’re going to switch topics entirely. Next question is from an anonymous listener. It’s a short question. “I had sepsis in pregnancy. My baby seemed unaffected by the infection and the drugs. I want to know how common that is.”

Okay. So, thank you for the question. Infections in pregnancy are really interesting for a lot of reasons. Not if you have one, obviously, but just from an academic perspective. And so, first of all, pregnant women seem to be more likely to get infections in pregnancy because one of the adaptations that the body has during pregnancy is that the maternal immune system is a little bit lowered. The thought is that it happens to sort of prevent the mother’s body from reacting to or sort of like attacking the pregnancy, meaning saying, oh, this is foreign. It shouldn’t be here and attacking it. So, one of the many mechanisms the body does to protect the pregnancy from the mother’s immune system is to lower her immune system, which is great for that. Not so great in terms of infections. So, there is a higher risk of getting infections.

Now, there’s sort of two ways an infection could affect the baby. The first way, which is probably not the more common way, but the one that people usually think of is will my baby get infected? Whatever infection I get, is the baby going to get the infection, and will it harm the baby either before birth, during birth, or after birth? So, that’s one question. And the second thing is, okay, even if the baby doesn’t get infected, can the infection in the mother, sort of in a different way, hurt the baby because it affects her sort of her blood pressure, her temperature, her pulse, like all the things that change when you get an infection, will that affect the baby? So, in terms of… So, that’s sort of the two questions.

Now, your question was specifically about sepsis, which is a very severe form of an infection where it’s not just having an infection, but in fact, you’re very, very ill, your blood pressure tends to be low, and your pulse is high, and you have high fevers. Most people with sepsis are in the hospital getting treated. That’s a very serious infection. So, what you had was a severe infection.

Now, whether the baby is going to get infected or not, a lot of it depends on exactly what is the cause of the infection, meaning what bug is it? Is it a bacteria? Is it a virus? Which one it is. I will say that if the mother gets bacteria in her bloodstream, it can definitely get to the baby, and we do see that in labor. When women have infections in labor, usually, that infection is from the uterus, from the membranes. We call it chorioamnionitis. Those babies most often are not born with an infection, but they can be, and have a higher rate of being born with an infection themselves. Meaning, bacteria in their bloodstream. And so, the pediatricians, whenever a mother is thought to be infected in labor, the pediatricians either treat the baby or test the baby. Again, depends on the circumstance. I’m not a pediatrician. Which circumstances they use is up to them, not up to me. But basically, that is something that is on their mind. If the mother has a bacterial infection in labor, they are going to be cognizant of that and make sure to either test or treat the baby for a bacterial infection after birth. Now, the mother’s not…if the baby’s not born, usually, as the infection in the mother clears, it clears in the baby as well.

Now, certain viral infections do get to the baby, certain ones don’t. The ones that do sometimes can impact the baby. And each one of these viruses or infections is its own topic, but there is always the potential that it can infect and affect the baby. And in others, it does not tend to affect them. And again, depends on the circumstances, like classically something like CMV, cytomegalovirus. We’ve talked about this before on the podcast. Does have the ability to impact the baby. But something like the flu does not typically directly impact the baby, for example. So, that’s sort of one way to think about it.

The other part of the question, though, is, well, let’s say someone has sepsis or they have a severe infection. And just even taking aside whether the baby gets the infection or doesn’t get the infection, any mother who is critically ill can impact the baby negatively because the baby requires blood flow from the mother through the uterus, through the placenta to the baby. And so, if there are issues with the mother’s blood pressure being too low, that can impact blood pressure, blood flow to the baby. Her pulse is very, very high to compensate for that. All part of the same picture that we’re worried about maybe decreased blood flow to the uterus to the placenta. Also, if the mother’s temperature is very high, the baby lives inside the mother. So, the baby’s…the room that the baby’s in, the temperature is going to go up. So, usually, the baby’s heart rate also goes up. So, often if the mother has a fever, we see the baby’s heart rate go up as well.

So, ultimately, whenever the mother has an infection in pregnancy, we’re trying to treat the mother so that she’s well. And then we have to figure and consider, is the baby being affected directly by this infection? Is the baby being affected indirectly by this infection, or is the baby not being affected at all? And based on the exact circumstances, we will see.

So, in terms of your question, when you said, my baby seemed unaffected by the infection and the drugs and medication, that is certainly a possibility. And how common it is really depends on all of the specifics. How far pregnant are you? Which infection is it? Meaning, is it a bacteria, is it a virus, which one of these? How sick are you? Is the baby born or not born afterwards? So, there’s all those factors that come into it, but certainly, again, the possibilities are the baby is in fact affected by the infection itself directly by the bug. The second possibility is that the baby’s not infected by the actual bug, but is affected indirectly because of changes in the mother’s physiology. And the third option is that the baby’s not impacted at all, which is obviously the best of the three options, and hopefully, the one that it is and what our goal is if we’re trying to treat a maternal infection, at least in terms of the baby.

Okay. Our last question today is from Sarah [SP]. “Thank you for your awesome podcast. It is incredibly informative, and I always look forward to Mondays and new episodes of the ‘Healthful Woman’ podcast.” All right. Sarah, thank you. “I have a question that I’ve always found interesting. I’ve been overweight for most of my life, and also have a strong family history of diabetes. During each of my pregnancies, I failed the glucose tolerance test and was diagnosed with gestational diabetes. While taking the test, I usually feel extremely unwell, and I’ve even felt close to passing out, almost as though my body cannot tolerate the glucose drink. What confuses me is that, outside of pregnancy, my A1C levels are consistently normal.” For our listeners, that means she does not have diabetes or prediabetes.

“I’m currently postpartum, and my doctor recently checked my A1C again, which was completely normal and not even in the prediabetic range. My question is, why would someone consistently fail glucose testing during pregnancy and develop gestational diabetes while still having normal A1C levels outside of pregnancy? Thank you again for all the education and reassurance you provide to your listeners.” Thank you, Sarah.

Okay. For your question. So, I would say that your situation is actually common. Meaning, for most women who get gestational diabetes, by definition, in pregnancy, even if they get it in multiple pregnancies, they are not themselves diabetic or prediabetic outside of pregnancy. Because gestational diabetes is not the disease diabetes, the condition diabetes. It’s specific to pregnancy, which is why it’s called gestational diabetes. And the reason it happens is, essentially, the hormones of the placenta that affect a pregnant woman’s sugar metabolism, and it does it for all pregnant women, it’s just done it a little bit more than in everybody else.

So, in pretty much all pregnant women, the placenta hormones are going to affect how she metabolizes and processes sugars. Usually, it slows it down, but it’s usually to a certain degree. Gestational diabetes is when we think it’s gone overboard, and our main concerns…and then we’ve had podcasts on gestational diabetes and on this. But our main concern for that is the sugar is too high. Maybe the baby’s going to grow too large, increase the risk of C-section, maybe birth injuries. There can be other potential issues. Then our second thought is, well, maybe the mother actually has a form of diabetes or prediabetes.

But in fact, when you look at women with gestational diabetes and you test them after delivery, I mean between pregnancies, the majority of them are going to test normal, that they don’t have diabetes when they’re not pregnant. They don’t even have prediabetes when they’re not pregnant. It’s just that when they get pregnant, they seem to be affected more by the placental hormones or at least their blood sugars are affected more than somebody else’s.

Now, why is that? You know, we don’t know for some degree. Some of it might be family history. Some of it might be related to body weight. Some of it might be people who are sort of borderline PCOS or something. Some of it might be people who are not prediabetic, maybe they’re pre-pre-prediabetic. There’s a lot of reasons why it could be, and one of those is we just don’t know.

Now, it is true that if someone has gestational diabetes, particularly if they have it in multiple pregnancies and the worse it is during pregnancies, meaning how bad is it to need to be on insulin, is that there is an increased risk in their lifetime of developing diabetes. Meaning, Sarah, someone like you who’s had it in two pregnancies but is not a diabetic or prediabetic, you do have a risk in your lifetime 10, 20, 30 years from now of getting diabetes or prediabetes. It does not mean you will get it. It just means your risk is a little bit higher. And why that is, we don’t think that it’s the condition gestational diabetes like harming you such that you get it later in life. We just think that, probably whatever risk factors lead someone to get gestational diabetes, known or unknown risk factors, are yours. And those are the same risk factors that would lead you 20 years from now to get diabetes or prediabetes or something like that.

For example, if there’s some sort of family history and some sort of genetic predisposition to insulin resistance or something like that, again, that’s vague, but let’s just say conceptually, there’s some sort of family history or some sort of genetic reason why someone would be more susceptible to insulin resistance, A, that would show up in pregnancy and, B, that could show up later in life. So, it’s the same risk factor for the two conditions. One condition is gestational diabetes, one condition is diabetes in life, but they don’t have to happen at the same time. And I think that your situation, as I said before, is actually the most common. So, I don’t want you to think that you’re sort of unusual in that aspect. Meaning, most women who will get gestational diabetes, even recurrent, do not have diabetes or prediabetes, although there might be a higher risk of it later in life. Doesn’t mean you will get it, but it’s just sort of a slightly higher risk.

And so, that’s something I always advise people if they’ve had gestational diabetes, to make sure that that’s part of your medical record. So, if you see an internist, family practitioner, general health, whatever it is, and they ask about your medical history, you could say, I don’t have diabetes or prediabetes. But just so you know, I’ve had gestational diabetes twice. And they should note that in the record and know that you probably need to be screened for diabetes later in life more frequently or differently than somebody who has not.

All right. Thanks, everyone, for your terrific questions. We’ll see you all next week.

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