Some fetal conditions lead to adult disease

[00:00:00] Host Amber Smith: Upstate Medical University in Syracuse, New York invites you to be "The Informed Patient," with the podcast that features experts from Central New York's only academic medical center. I'm your host, Amber Smith. Today I am talking about the importance of fetal development with Dr. Timothy Canvan, professor and chair of obstetrics and gynecology at Upstate. Welcome to "The Informed Patient," Dr. Canavan.

[00:00:25] Timothy Canavan, MD: Thank you for inviting me.

[00:00:27] Host Amber Smith: I know your area of expertise is maternal and fetal medicine. So let's start by talking about fetal growth. How does a woman and her doctor know that her baby is developing in a healthy way?

[00:00:39] Timothy Canavan, MD: So, doctors do a number of things when people come in for a prenatal visit to make sure that the baby is growing effectively.

First, you focus on the mother, so we get the mom's weight. We get her urine to check and make sure that's good. We get her blood pressure. And we measure her fundal height, which is the size of her belly, how big is her belly getting. We actually measure it from the bone, just under your belt buckle to the top of the uterus, which by five months is about at your belly button. And just making sure that that is slowly increasing in size as the woman gets more pregnant.

[00:01:20] Host Amber Smith: And then what about the baby? How are you able to monitor the baby's development?

[00:01:25] Timothy Canavan, MD: So the baby's growth is partially by the fundal height, but also women will get a routine ultrasound in the majority of cases around five months. So that will take a look at the size of the baby. The size of the baby is determined by comparing the baby on that ultrasound to other babies that were considered to be normal at birth, comparing the sizes of various things, the size of the head, the size of the belly, the size of the upper part of the leg to normal women that had normal births, to make sure the size of the baby is where we would expect it on that ultrasound.

Whether we get another ultrasound depends on other things like the mom's weight gain and her health and the fundal height as to whether we might check the size of the baby later. But a majority of women do get a second ultrasound or sometimes a third one later in pregnancy to monitor the actual size of the baby.

[00:02:20] Host Amber Smith: So is five months, at that first ultrasound, is that the earliest that abnormalities are detected typically?

[00:02:28] Timothy Canavan, MD: Most of the times that's the ideal time to start with looking at the baby with ultrasound. It's big enough now that at that point we can get measurements that give us more information about the size of the baby. But you can actually detect growth abnormalities, even going back to four months, which would be 16 weeks. And so sometimes we will do that in women that have had early pregnancy complications in the past or are at risk to have pregnancy complications.

[00:02:55] Host Amber Smith: What are the most common abnormalities in fetal growth?

[00:02:59] Timothy Canavan, MD: So fetal growth is kind of evaluated in two aspects. One is referred to symmetrical growth restriction, or basically slowed growth. Everything is small, and that usually indicates a certain classification of problems, as opposed to asymmetrical growth where the baby is favoring growth of the heart and the brain. So the chest and the head tend to be a fairly normal size, but the rest of the baby, the limbs are small because the baby is shunting blood nutrition to the heart and brain in favor of those organs because there is an environment of low nutrition that the baby recognizes and therefore is shunting the blood to those particular organs because they're the most important, and you end up with an asymmetric growth pattern.

[00:03:53] Host Amber Smith: So if you notice that asymmetric growth pattern, can it be corrected in the last part of the pregnancy?

[00:04:02] Timothy Canavan, MD: There's certain things we do, but we can't completely fix it most of the times. But certainly if the woman is in a situation where her nutrition is poor, and that happens in countries in war torn areas where nutrition is hard to get by, people who are in poverty and have food scarcity, which happens in the United States as well. You know, sometimes if we recognize that, we can use nutrition to drive fetal growth and we can correct some of that.

Those babies that are undernourished tend to be symmetrically small, although not always. Babies who are small asymmetrically -- this may be due to a placental issue. It may be due to a maternal issue, like the mom has a poor heart, or she has diabetes, or she has lung disease, or she's had an event in her pregnancy that has affected her lungs, like COVID, that have resulted in the baby getting a sudden loss of nutrition, and therefore asymmetric growth restriction can occur.

[00:05:01] Host Amber Smith: Can you detect cancer before a baby is born?

[00:05:05] Timothy Canavan, MD: In terms of the baby having cancer?

[00:05:07] Host Amber Smith: Right.

[00:05:08] Timothy Canavan, MD: We can see tumors growing, so we can know that. We can't pick up all types of cancers, but the majority of cancers in babies tend to lead to growths that we can clearly see on ultrasound. And so we know that we have a problem, basically on the fact that there's a mass growing.

[00:05:26] Host Amber Smith: What do you ask moms to do to reduce the risk of birth defects?

[00:05:32] Timothy Canavan, MD: The most obvious, and anybody who's been pregnant gets this kind of discussion with their. Doctor, is obviously you want to avoid cigarette smoking, tobacco use in general, vaping. We're a little skeptical about vaping because we're just not exactly sure what's in those fluids that people are vaping. Some of it's nicotine, but a lot of it's chemicals that provide flavors that we don't know what it does in pregnancy.

Alcohol consumption can cause problems. Medications, there are some medications that can affect babies and so if you're on a medication for a medical problem, you should talk to your doctor. You shouldn't just stop the medicine because the disease might be more dangerous to the baby than the medication. So it has to be checked.

We also like women to take folic acid before they actually conceive in order to protect the nervous system, which relies on folic acid for regular development.

Clearly light exercise is important. You don't want to start an exercise program once you're pregnant, but being in good physical condition, a good weight, is also important. All these kind of things reduce the risks for growth problems and birth defects prior to getting pregnant. That's why we really want women to think about being pregnant, prepare, and then get pregnant, which doesn't usually happen, but we always like to try to encourage it.

[00:06:49] Host Amber Smith: This is Upstate's "The Informed Patient" podcast. I'm your host, Amber Smith. I'm talking with Dr. Timothy Canavan, the professor and chair of obstetrics and gynecology at Upstate.

I'd like to ask you about heart defects. How often are babies born with a heart defect?

[00:07:06] Timothy Canavan, MD: Heart defects occur in approximately one in every hundred pregnancies. The actual is actually 0.8%. So just about 1% of moms who get pregnant have a baby with a heart defect.

[00:07:17] Host Amber Smith: And can you detect this before the baby's born?

[00:07:20] Timothy Canavan, MD: They usually detect heart defects at that 20 week, that five month ultrasound. Although ultrasound can only pick up about, say, 70% to maybe 80% on a good day of heart defects in babies. Some heart defects are too small or do not manifest obviously an ultrasound until later in the pregnancy. So at 20 weeks, it's about 70% that we can pick up heart defects.

[00:07:45] Host Amber Smith: Now, are these generally problems with the heart valve or the heart pumping function? What is typically a heart defect? What does that typically mean?

[00:07:55] Timothy Canavan, MD: There's two classifications of heart defects. One is structural, and that's what we pick up the most, the most common one being a ventricular septal defect, which is a hole in the little membrane that separates the two sides of the heart. And although that's the most common, it's also the least problematic. Many of those will close spontaneously without any intervention by physicians, like surgery.

The other things are problems with the valves where a valve is too small, where a valve doesn't develop, or where the big blood vessels that come out of the heart do not go in the right directions. You know, the right side of the heart should feed the lungs, and the left side of the heart feeds the body with blood. And sometimes those two sides do not orient themselves right, and you have transposition, or the vessels switch, and the left side of the heart is pumping blood into the lungs, and the right side of the heart is pumping blood around the body. So there's a number of different types of heart defects that can occur.

[00:08:53] Host Amber Smith: And are most of them treated surgically after the baby's born?

[00:08:58] Timothy Canavan, MD: There are some which require no intervention, like the small hole between the two sides of the heart can close spontaneously. Critical heart defects -- which are about one in every four babies who have a heart defect, have a critical heart defect -- those are almost always treated surgically. Some of them are very complicated. Some of them require more than one surgery to repair.

[00:09:22] Host Amber Smith: Can you explain what the placenta is and its role in congenital heart disease?

[00:09:28] Timothy Canavan, MD: The placenta sort of takes two roles. The first is, its primary role is nutritional support of the pregnancy, so it provides oxygen and nutrients to the baby so that it grows effectively. It also sort of protects the baby. It provides an isolated environment so that another person can grow within a person and not be rejected, right? Because when you give an organ to somebody, you have to give them medication to protect that organ because our body wants to destroy it. A baby is a foreign body too, and so the placenta protects that.

The other thing the placenta also performs is, it provides fluid that surrounds the baby. Some of the fluid does come from the baby as well. The placenta also is sort of the black box of the pregnancy. It sort of gives us a historical record of how the pregnancy proceeded so that doctors can sometimes use the placenta to figure out why a baby didn't do as well as we perceived it should have. And so it's sort of a retrospective way for us to investigate a pregnancy that may have had some complications.

[00:10:35] Host Amber Smith: Can you tell us about the fetal origins of adult disease hypothesis?

[00:10:40] Timothy Canavan, MD: So there was a physician in the UK, the United Kingdom, England, who in 1986 was looking at ischemic heart disease, so heart problems like heart attacks, blocked blood vessels, in Wales and England. He noticed that the rate of ischemic heart disease in older adults, 50-, 40-years old, correlated with neonatal or baby deaths in the same areas. And when he looked, he found that babies that had poor nutrition or babies that had very poor growth, either during fetal life, pregnancy, or shortly after neonatal life, had a higher rate of ischemic heart disease in these geographic areas.

And so he hypothesized that there is a fetal origin to adult disease, and that's where that hypothesis came from. He published his paper in 1986 in Lancet, which is an English publication, a medical journal, and this is where that whole hypothesis came about, that a fetus or a neonate that has poor nutrition or poor support of growth can lead to adult diseases.

[00:11:51] Host Amber Smith: So is this seen in both developed and developing countries, equally?

[00:11:57] Timothy Canavan, MD: Yeah, it's seen equally throughout the entire world. It's seen more obviously in developed countries because our health is better. So when someone has poor health, it's easily recognized. And in developing countries, countries that have a lot of poverty, there's a lot of disease related to the poverty itself and the infrastructure of those countries. So it's a little hard to tease out, but it occurs universally. It's a human, it's a human being problem, in terms of fetal growth and adult disease.

[00:12:30] Host Amber Smith: So in addition to heart disease, what are some other examples of fetal conditions that lead to adult disease?

[00:12:38] Timothy Canavan, MD: So, nutrition and fetal growth seem to be the primary factor that influences later disease in adults. But most of the times it's ischemic heart disease, diabetes, obesity, and some people have related it to possibly blood pressure and stroke. Although the data on those is a little weaker, probably because there's a number of factors that would play a role in those problems, not just the fetal origins, but also our environment and our lifestyle. But those are the major things that influence the fetal origins of adult disease.

[00:13:16] Host Amber Smith: So are you saying that things like the mom's, when the mom is pregnant and if she chooses to smoke or she has a bad diet or she doesn't exercise, does that contribute to later adult disease for her child?

[00:13:30] Timothy Canavan, MD: There is an hypothesis that yes, it does. More than likely it is severe malnutrition that either comes from food scarcity as a result of poverty or potentially war torn areas or areas that have plagues or major disease factors that result in women having an environment that's not as protective for a healthy pregnancy. Maybe the woman doesn't smoke, but she lives in a home with five other people that smoke. And so she's exposed to secondhand cigarette smoke, which people don't pay a lot of attention to but can certainly be almost like smoking.

Women who have drug disorders. That's why we're very aggressive trying to help women who have opiate use disorder and addiction because those kind of things lead to women not paying attention to their health. It's not only that they take a drug that affects their cognitive abilities, it also makes them not pay attention to their own health. So it's really related to nutrition and the health of their environment.

[00:14:32] Host Amber Smith: What about stress? because I'm thinking of, like you mentioned, the war torn countries and the stress. Does that have an impact on the developing baby?

[00:14:40] Timothy Canavan, MD: Accumulating evidence that significantly stressful environments for women who are pregnant affect fetal growth and development.

I don't think the data is as conclusive as it is for malnutrition, but certainly women who are under the significant stress and that could be living in a home where there's a violent individual, not just in a war-torn country with that day in and day out stress of possible being the recipient of violence or mental abuse can certainly have an adverse effect on fetal development. And that goes even into behavioral health and mental health for women who are pregnant, who have significant environments that lead to mental health disorders, probably that affects their fetal development and growth.

[00:15:23] Host Amber Smith: So can proper prenatal care reverse this?

[00:15:28] Timothy Canavan, MD: Certainly there is a point at which there is no return, so certainly early good prenatal care can prevent these outcomes. Once we start seeing these kind of changes, it's very hard for us to reverse them unless it's a significant malnutrition issue. Certainly taking women out of stressful environments, putting them in safe environments, getting them good nutrition definitely improves their outcome for their pregnancy, regardless of when we identify those problems. But there is a point at which we can't really make a big change. You know, once you're within the eighth month of pregnancy, we're probably not going to be able to have an impact on that.

[00:16:06] Host Amber Smith: Well, Dr. Canavan, your work is very interesting. Thank you for taking time to tell us about it.

[00:16:11] Timothy Canavan, MD: You're welcome. And I'm delighted to have gotten an opportunity to speak a little bit about the health and wellbeing of pregnant women.

[00:16:17] Host Amber Smith: My guest has been Dr. Timothy Canavan, professor and chair of obstetrics and gynecology at Upstate. "The Informed Patient" is a podcast covering health, science and medicine, brought to you by Upstate Medical University in Syracuse, New York, and produced by Jim Howe, with sound engineering by Bill Broeckel and graphic design by Dan Cameron. Find our archive of previous episodes at upstate.edu/informed. If you enjoyed this episode, please tell a friend to listen, too. And you can rate and review "The Informed Patient" podcast on Spotify, Apple podcasts, YouTube, or wherever you tune in. This is your host, Amber Smith, thanking you for listening.