Mailbag 30: 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, our 30th “What Does the Fox Say?” Okay. Our first question is from Meghan. “Is it safe to whiten/bleach teeth during pregnancy? I’m in my second trimester, and would like to bleach my teeth. Google says no. My friends say yes. Who’s right? Google or friends? The specific brand I’ve been using is a 15% prefilled teeth whitening trays hydrogen peroxide.” In her question, Meghan went into brands, but I don’t want to either go pro or con on any particular teeth whitening brands. Not like I would know what’s better than the other. I don’t.

All right. In terms of your question, it’s a good question. My short answer would be, it should be safe. So, I’m going to side with your friends as opposed to the Google. You know, hydrogen peroxide, part of the reason you might find on the Google that it’s not safe in pregnancy, that’s really if you ingest it, like if you start guzzling hydrogen peroxide, which probably isn’t good for you if you’re not pregnant, too. But, you know, things that you’re just going to put on your skin or on your teeth or whatever, you know, should not be an issue. Right? What would be the concern is if somehow enough of this got in your system, got in your bloodstream, traveled through your bloodstream to the uterus, to the placenta, and got to the baby, and hurt the baby. But it doesn’t really get in your bloodstream.

If you think about it… For example, what I typically will tell people when I’m going over examples like this is, you know, Purell. Right? It’s like pure alcohol. Right? So, you don’t drink alcohol in pregnancy. It’s not good, but we rub it on our hands all the time in pregnancy. And that’s not a concern. Why is it not a concern? Because it doesn’t get absorbed through your skin and into your bloodstream as alcohol. You don’t get drunk by rubbing Purell on your hands. And so, it’s not really going to be a concern for the baby.

Similarly, let’s say you fell and cut your knee, and you’re there, and the doctor or whatever, nurse or whoever, they’re putting hydrogen peroxide on the wound to clean the wound. No one’s going to be concerned if you’re pregnant, that’s going to get, like, absorbed into your bloodstream and harm you or the baby. Right? It’s superficial. It’s topical. It’s on your skin. It’s fine. You know, similarly like nail polish, right? You put it on your nails, but you don’t eat it. That’s where a lot of the data on, like, hair dye, for example, where people were concerned, but it doesn’t really get absorbed into your bloodstream. It’s just on your hair.

So, the same thing if you’re whitening your teeth, it’s really just going on your teeth and that’s it. It’s not going into your bloodstream, not going to the baby. So, I doubt there’s extensive studies on this that would prove what I’m saying, but in general, I would not have a concern with someone whitening their teeth in pregnancy. Why not have a good, nice, white smile for all those photos you’re going to take?

All right. Our next question is from Meaghan. Now, I’m from the Midwest, and I have a hard time pronouncing any names like Meghan, Meaghan, Maegan [SP], whatever it might be. The reason I believe that our first listener’s name is Meghan and our second listener’s name is Meaghan is the spelling. The first is M-E-G-H-A-N, which I pronounce as Meghan, and the second is M-E-A-G-H-A-N. So, I’m going with Meaghan. That A in there makes it Meaghan.

All right, Meaghan. “Hi, Dr. Fox. I’m a loyal Toaster and now loyal follower of the ‘Healthful Woman’ podcast as well.” Thank you, Meaghan, for that. If I’ve been mispronouncing your name this entire time, I apologize. “My question is, for a normal uncomplicated pregnancy, would you recommend a repeat cesarean for baby number three, or attempt a VBA2C,” that’s like a VBAC with a two in the middle, “For someone wanting four children? My first pregnancy was an unplanned C-section due to low fluid and postdates. My second C-section was a failed VBAC after a 27-hour induction. No health complications, easy, uncomplicated pregnancies, and I’m 29 years old. My husband and I always wanted four children, but I’m also very active, love running, etc., and don’t want to risk long-term issues with too many C-sections. I live in New Jersey, which is not very VBA2C friendly.” Whoa. Shots fired on the State of New Jersey. All right. I live in New Jersey.

Okay. Fine. So, in terms of your question, basically, it’s you’ve had two prior C-sections. What should you do with the third? It’s a conversation, and it depends a lot on the specifics. I will tell you an interesting fact. Probably about 10 to 20 years ago, the American College of OBGYN, which puts out all these, like, practice bulletins and statements and whatnot, had one on VBAC. And at the time, they had written that, if you have two prior C-sections and no prior vaginal deliveries, that you should not labor and you should have a third C-section. And then they updated it and, you know, about 10 whatever years ago and they said, if you’ve had two prior C-sections, you can have a vaginal delivery for your third. What changed between the first recommendation and the second? Nothing. There was no new data that came out to support this. They just sort of changed their minds, which I thought was pretty cool and interesting.

So, the reason it’s a conversation is the following. So, for those of you who are listening and don’t know what we’re talking about, VBAC is vaginal birth after cesarean. It’s basically way, way, way, way, way back a long time ago when someone had a C-section, they were told you should never deliver vaginally, you should only have C-sections. And then people pushed back on that and said, well, maybe you can, maybe it’s safe. And we now have this whole…we’ve actually done a full podcast on this, where there’s a lot of people who it is a safe option and they can deliver vaginally after a C-section. There are some risks associated with it. And so, that’s always a conversation.

And so, whenever we’re talking about VBAC… And I will get to your specific question, Meaghan, in a second. But just as background, whenever we’re talking about VBAC, we’re sort of trying to balance what is the risk of doing the VBAC and what is the risk of just scheduling a C-section. And for most people…and there are exceptions. For most people, both options are safe for the mother and baby, and both options are likely to go well. If you are trying for a VBAC, the positive is that if you’re successful, you can have a vaginal delivery, makes your recovery typically easier. For your future births, it’s easier to have vaginal deliveries.

The downside to trying a VBAC is, number one, you could end up laboring and having a C-section anyways, like you had, Meaghan, which isn’t…whether you call that a risk or a consequence sort of depends on the semantics of it. But you could end up laboring for a long time and ending up with another C-section, which certainly could be annoying. Right? You’re like, man, if I could go back, I’d rather just have the C-section scheduled. Potentially, the C-section could be harder because you’ve been laboring for a long time, maybe a tougher recovery than if you just had it scheduled. And then the other risk is, while in labor, you could have something called a uterine rupture, where the scar on the uterus opens up in labor, which is not safe for the mother, not safe for the baby. Then you have an emergency C-section, fine. The chance of that happening, that uterine rupture, typically is about 1%-ish. It could be slightly higher, slightly lower, but it’s somewhere around there.

On the other side, if you do a C-section, a scheduled one, well, the plus side is you’re very unlikely to have a uterine rupture. You’re not going to have a long labor and end up in a C-section. Fine, it’s scheduled. The downside is, well, you’re for sure having a C-section. And so, you’ll have all the pain from recovery, and for your future births, makes it more likely to have a C-section.

Okay. So, the question is, so, that’s sort of when you have one prior C-section. What happens if you’ve had two prior C-sections? And so, what ultimately happens, it seems, is that, number one, the chance that you’re going to have a successful vaginal delivery goes down compared to if you just had one prior C-section. And, number two, the chance of a uterine rupture goes up. Doesn’t go up a ton, but it goes up. So, maybe if it was 1% after one C-section, it’s probably about 2% or so after two C-sections, maybe slightly lower, maybe slightly higher, but these are very sort of broad numbers.

And so, when we have a conversation with someone who’s had two prior C-sections, it’s the same conversation sort of in principle as for someone who’s had one prior C-section, but the numbers are different. So, whatever the chance was of a successful vaginal delivery after one, it’s going to be lower after two. And whatever the chance was of a uterine rupture after one, it’s going to be higher after two. And so, that might change someone’s calculus and how they decide.

Now, obviously, there are some things that might change the numbers. For example, let’s say, someone had a C-section, then a vaginal delivery, then a second C-section. Well, that person’s already had a vaginal delivery. So, their chances are improved for a successful VBAC after the second C-section versus someone like you, Meaghan, who’s only had two C-sections and no vaginal deliveries. So, your chances would be lower.

Also, when we look at someone’s C-sections, we look at what is the reason they had a C-section. So, someone had a C-section because the baby was breech, let’s say, and the second C-section was maybe because they were twins and one of them was breech. And now, they have a third pregnancy. Well, they’ve never really tried to labor, so to speak. But for someone who has labored, like you said, for 27 hours and didn’t have a vaginal delivery, the numbers tend to be a little bit worse, which makes sense. You know, you can quantify these things and put numbers to it, but sort of as an overall gestalt, for someone who’s had two C-sections, no vaginal deliveries, and their second C-section was a failed VBAC, it does not mean that you can’t have a VBAC or you won’t have a VBAC. It just means your odds of successfully having a VBAC are a little bit lower, and your odds of a uterine rupture are a little bit higher.

So, that’s a decision. Is it worth it to try? And that decision is something that is obviously very important when you think about it. But as you said, there are some doctors or hospitals who are not comfortable with those numbers, and would not want you to do it. And so, you would…if you want to do it, you would have to find a place that was comfortable doing it. In our practice, we do “let” people who’ve had two prior C-sections and no vaginal deliveries try for a VBAC, but our counseling is different. We’re a little bit more cautious. We’re much less likely to induce that labor, for example. But it’s not off the table, so to speak.

So, for you, is it worth it or not? And you’re asking whether having a third and then maybe a fourth C-section is going to impact your ability to be active, and healthy, and whatnot. And it really shouldn’t. I mean, obviously, if there’s some complication from the C-section, I mean, maybe that can impact your long-term health, but that could also happen if you’re trying for a VBAC, right? So, it’s not like one…you know, road A is to try for the VBAC, and road B is to just have the C-section. It’s not known that one versus the other is more or less likely, you know, to end with you having some sort of long-term consequences or the inability to run, and all these things. Typically, once you recover from a C-section, whether it’s your second, third or fourth, you should be fine in the long-term in terms of all of those things.

So, I guess, short answer to your question is, it depends. It depends on what you want, what your risk tolerance is, who your doctor is, what hospital you’re delivering at. And I would say, it’s an option potentially, but it has to be something that you want to do and that you’re okay with sort of the risks and the likelihood of success as compared to having that scheduled C-section. And again, that requires a conversation between you and your doctor, or maybe you and several doctors till you find the right one who’s on the same page as you, if that’s what you want.

Okay. Next question is from Victoria [SP]. “I’m three months postpartum with a healthy baby boy. Congratulations. I received a positive trisomy 22 result through NIPT at 12 weeks, resulting in high-risk MFM appointments biweekly until birth, and then further chromosomal analysis to rule out trisomy 22. Obviously, trisomy 22 is not compatible with life. So, I spent the majority of pregnancy fearing the worst. Just wanted to share because I did not find many cases of this on the internet for reassurance or support during my pregnancy except for this podcast.”

Thank you, Victoria. Wasn’t exactly a question. It was more of like a statement, but I’m turning it into a question because I think this is a really important topic that you brought up related to screening for chromosomal abnormalities in pregnancy versus testing for chromosomal abnormalities in pregnancy. So, what’s the difference?

Testing is when you do a test and you know the results, you know what the answer is. So, when we’re talking about genetic conditions in the baby before birth, the tests that we have are diagnostic, you know yes or no, and they are invasive. It’s either a CVS or an amniocentesis. And the reason that those are diagnostic is because you’re actually getting DNA from the baby, or in the case of CVS, from the placenta. And you’re testing it, and you’re finding out what is the status of this baby.

And so, if you’ve got an amniocentesis, let’s say, where it said the baby has trisomy 21, then the baby has trisomy 21. It’s just as accurate as if after birth you did a blood test or a cheek swab or a hair sample, whatever it is on the baby. It’s just as accurate. That’s to be contrasted with screening in pregnancy, which is what you’re referring to in the NIPT, which is a blood test. For NIPT, there’s also ultrasound, and those don’t tell you definitively does the baby have a genetic condition. It just screens you to tell you, are you high risk? Are you low risk? You could put a numerical value on how high risk, how low risk. But it tells you, sort of points you in one direction, but does not give you an answer.

So, for example, if I had someone who had an NIPT test, which is a blood test, that said your baby’s high risk for trisomy 22, what I’ll tell them is, okay, this test says you’re at high risk for trisomy 22. But if I do an ultrasound, baby looks perfectly normal, is perfectly fine, it’s hard to imagine that the baby actually has trisomy 22 because, as you said, it’s not even compatible with life. There aren’t people walking around the planet with trisomy 22.

So, it means one of three things. It either means the test is completely wrong, which happens, right? It’s a low percent, but it does happen, which would be great. There is a possibility that the baby has something called mosaic trisomy 22, which is where the baby’s DNA, some of the cells are normal and some of the cells are trisomy 22. That’s a mosaic, where not all of your cells are the same. And that’s a possibility. Like, how could the baby sort of look normal, but have this result come up? That could be diagnosed during pregnancy with an amniocentesis, for example, or after birth with genetic testing. Or the third option is that since the cells in the NIPT that we get from the mother’s blood come off the placenta, it could be that the placenta has some trisomy 22 in it, but the baby has none of it.

And so, that’s sometimes we get that either with an NIPT or sometimes with a CVS because we’re testing the placenta. And we’ve had podcasts on this before, something called placental mosaicism, where there’s a genetic abnormality in the placenta. And that’s one of the situations where the DNA of the placenta does not match the baby. And so, that’s…you know, what could you do about that? Well, if we suspect it, you could then do an amnio because that’s not testing the placenta. And if the placenta shows the trisomy 22 cells, but the amnio does not, you’re pretty confident it’s only in the placenta and whatnot.

So, what I would suspect for you, Victoria, is that your NIPT was either completely false, or since your baby’s perfectly healthy, I highly doubt that there’s a mosaic 22 in the baby. But there’s a good chance that the placenta had some mosaicism in it, and that could have caused the results on the NIPT in an otherwise perfectly healthy baby. You would know that after birth if they sent the placenta for genetic testing, the placenta specifically as opposed to just testing the baby. But it is very important, and this is one of the things we talk about genetic screening all the time. It’s just a screen. It’s not the answer. It just points you in one direction. The other, it’s very, very reliable for certain things, but it’s not 100%.

And so, particularly, if there’s something that’s abnormal, we don’t sort of counsel and act on the blood test alone. We have to look at all the information to get a sense of, do we think this is correct, incorrect and what are we going to do about it?

Okay. Next question is from Camilla [SP]. “Hi, Dr. Fox. I was diagnosed with severe IUGR, intrauterine growth restriction, at 32 weeks, and ended up having a C-section at 36 weeks and 2 days to deliver a beautiful and tiny 4-pound baby. Thankfully, he’s now thriving and growing well.” Terrific news. Glad to hear that. “As I start thinking about baby number two, I’m hoping to better understand what, if anything, I can do to reduce the risk of recurrent IUGR. I’m a healthy weight, eat a well-balanced diet, stay active, don’t smoke or drink.” Wow, living the good life, Camilla. “So, I don’t have any of the typical risk factors. For more context, if it’s helpful, the placental pathology revealed a small third trimester placenta.”

Okay. Good question. Basically, you, Camilla, and anyone who has a baby who is growth-restricted, you know, sort of much smaller than we would expect, what is the chance that’s going to happen again? What could we do to prevent it again?

So, for most people who have a baby who’s growth-restricted, either…and I’m not saying this is the case with you because you were born…your baby was born at 32 weeks. But for most people, either the baby’s perfectly fine, and it was just small, sort of some babies are built small, or if there’s something going on, it was related to the placenta, that the placenta wasn’t functioning well. There are other reasons why babies could be small, certain genetic abnormalities, infections, and whatnot. Those tend to fortunately be less common, but they’re possible. But the main two are either the baby’s perfectly fine and just small, or there was a problem with the placenta causing the baby to be smaller than expected. I’m guessing, if your growth restriction was severe and started at 32 weeks, and you ended up getting delivered at 36 weeks, it’s probably the placenta. But I couldn’t say that for certain, but fine.

So, if you have a placental cause that leads to severe growth restriction, there is a chance of recurrence that could happen again, more likely than somebody else on the planet, but it’s still less than 50%. Meaning, most people who have this are not going to have it again in the next pregnancy. And why is that? Because most of the time, it’s a one-off, it’s a fluke. It’s just for whatever reason, this placenta didn’t attach right, didn’t work right, wasn’t a great placenta, and so be it. That’s what happened, but it’s not like there’s anything wrong with you or your uterus or anything like that.

So, if that’s the case, then typically, there’s nothing you would need to do. Again, you are already living a good lifestyle. The things you mentioned are actually not really the main causes of placental issues anyway. So, yes, it’s great to eat a well-balanced diet. It’s great to have a healthy weight. It’s great to stay active. Those don’t typically cause growth restriction, fortunately. The fact that you don’t smoke or drink is terrific. Smoking could cause growth restriction. Fine.

So, the other risk factors tend to be things like having twins or having IVF slightly increases your risk of growth restriction. Having certain medical issues increases your risk of growth restriction. Obviously, you can’t control those. There’s one condition called antiphospholipid syndrome. Typically, it ends up being a little bit worse than what you had, but if you had that condition, then you could…there’s treatment for it in the next pregnancy.

But for most people, they don’t have any medical conditions. They’re perfectly fine. They’re healthy. There’s, like, nothing going on. And for them, there really isn’t a ton to do in the next pregnancy other than to continue to have a healthy lifestyle and maintain a normal diet and whatnot. Sometimes, we’ll give people baby aspirin in the next pregnancy, but it’s not really great data that it lowers the risk of growth restriction. It probably lowers the risk of preeclampsia, which it might be related, but it’s not known to do that, and just to make sure people get the right amount of nutrients and vitamins. But that’s not really typically the cause.

And also, some of this is complicated to tease out because, in a lot of the situations, when the baby is not small due to the placenta, but just small due to genetics, like this baby is small, people sometimes have small babies, that is likely to recur because everyone’s related. Right? So, if someone is… Let’s say, a couple, they were both small when they were born, and their first baby is small when he or she is born, the next baby is also likely to be small. But that doesn’t mean there’s a problem. So, it’s sort of…it’s hard to tease out in studies. Were the babies small because of a problem with the placenta or were the babies small just because they were small? And then if it was because of the placenta, maybe you can impact that in a future pregnancy. Though, as I said, probably not much you can do anyways. But if the baby is small for just, like, genetic reasons, no, you’re not going to impact that because that’s just the kinds of kids you have.

So, for you, Camilla, what I would say is, assuming you don’t have any medical issues and they sort of did all the tests and whatnot, there’s probably not much you can do, short of maybe taking a baby aspirin — although, again, I don’t know how much data there is to support that — and just maintaining your healthy life. The fact that the placenta was a little bit small, it could be that the placenta was the problem, and that’s why the baby was small, or it could also be sometimes just smaller babies have smaller placentas, which makes sense. Without other pathologic findings, that’s hard to know.

All right. Our last question is from Sarah [SP]. “I’m a Canadian Toaster.” All right. Canadian Toasters. Love it. “Who has been listening to your podcast ever since I heard you on ‘The Toast’ back in April. I have a question about a very sensitive, hot button issue, but I’m hoping you’ll still answer it.” Sarah, I’m going to answer it. “I’ve been going back and listening to your episodes about prenatal genetics. I’ve noticed that you and your guests never touch on the topic of abortion, at least not in the episodes I’ve listened to. Is it because you’re trying to stay apolitical or because every state has different laws, and your advice would not be consistently applicable across the country? I’m genuinely curious as abortion is something all doctors discuss freely and openly in Canada. I’m asking with a great deal of respect for you and everyone’s viewpoints, and coming from a place of curiosity.”

Okay. Sarah, it is a fair question, and I appreciate it. And I don’t take it for anything other than curiosity on this. And what I will tell you is, first of all, we definitely have discussed abortion on the podcast. We’ve had people talk about reasons that they have to terminate pregnancies. We’ve talked about it with certain podcasts related to findings in the fetus, whether anatomic or genetic. So, it does come up, and it is a part of obstetrics all over the country in terms of doctors. But, obviously, the counseling about abortion is going to be different based on the circumstances. And the circumstances include, yes, where you practice medicine and what state you are because there are certain just realities and legalities that people argue about in both directions. But those are the realities. If you practice in certain states, it might be different options available than if you practice in other states. But also, the population and who are the people coming. For some people, abortion is very much an option, and for other people, abortion is very much not an option, and everything in between.

So, medically, the conversation is sort of on our minds, but when it comes up, how it comes up, in what way it comes up, what are the options, will depend on all of those factors. Right? So, I practice in New York State, which has very liberal laws related to abortion. So, it probably comes up a lot more in conversation than maybe someone who practices in a state with much stricter laws on abortion. But also, the patients who I see, there’s a wide range of opinions on abortion. So, for people who it’s off the table, so to speak, there’s very little conversation about it because it’s not an option for them. They’re not interested. It’s not something they’re going to do. And fine, okay. And for others, who it is, the conversation is going to be there potentially, obviously, based on the medical circumstances.

In terms of the podcast, so, we don’t shy away from it, so to speak. But I generally do try to stay apolitical about it for a lot of reasons. But I would say, the main reason — and I said this on the podcast before — is the reason I do this podcast is to give good information to our listeners, whether they’re my patients or not my patients around the country, around the world, whatever it might be. And I don’t want the podcast to be a place where people on either side of this discussion, let’s call it, feel uncomfortable or unwelcome.

And so, I really try to avoid either conversations or topics or situations, where people are going to start, whether it’s myself, or whether it’s my guests, or whether it’s anyone else, giving…talking about a situation or giving opinions that are very much on one side or the other of this conversation, this debate, because I don’t want people who are listening to feel like this podcast isn’t for them. They’re unwelcome. They shouldn’t be listening because it…ultimately, my goal, my mission for this podcast is not to drive the conversation around abortion one way or another. It’s to give people good information to make decisions.

Now, do I always get it right? Could I talk about it more? Should I talk about it less? Yeah. I’m not perfect. And, obviously, maybe people will disagree on how we’ve done it over the years in one way or the other. And I totally respect that. And I don’t claim that the way we’re doing it is obviously the best way, but that’s sort of been my reasoning, that I just want it to be a place where everyone feels welcome. And there are other places to have those conversations which are very, very important, and have those discussions and debates and whatever it might be, whether they’re political, whether they’re legal, whether they’re moral, religious, whatever it might be. I think those are very important. But it’s really not what I wanted this podcast to be. So, I will absolutely discuss it because it comes up in medicine, and it comes up in our decisions, and that’s totally appropriate. But I try not to sort of focus on that as a point of discussion in the podcast just so that people don’t get upset by it, so to speak, in either direction, obviously.

So, there’s my answer as honest and candid as I could be. I really do appreciate the question. Other people have asked me that in person and, you know, patients of mine, and that’s the same answer that I give them. But thank you for the question.

All right, everyone. Thank you very much. We’ll see you all next week.

Thank you for listening to the “Healthful Woman” podcast. To learn more about our podcast, please visit our website at www.healthfulwoman.com. That’s healthfulwoman.com. If you have any questions about this podcast or any other topic you would like us to address, please feel free to email us at hw@healthfulwoman.com. Have a great day.

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