LISA BODNAR, PHD, MPH, RD
CTSI recently sat down with Lisa Bodnar from the University of Pittsburgh School of Public Health’s Department of Epidemiology to discuss risk factors for pregnant women and how they can be reduced.
CTSI: Briefly describe the problem of infant mortality (defined as a baby’s death during the first year of life) in Allegheny County.
Dr. Bodnar: The disparity we see in infant mortality rates between African Americans and Whites in Allegheny County is striking. It’s far worse than in other counties in Pennsylvania, let alone in other parts of the country. Putting that in context, the infant mortality rates overall in the U.S. are much higher than in many other developed countries. So, the fact that the rates in the U.S. are high—and knowing that the rates in Allegheny County are very high, and the disparity in those rates is even higher—is staggering and tragic. We absolutely have to do something about it.
CTSI: Please give us an overview of your work with vitamin D and its possible connection with infant mortality.
We used to think vitamin D was only important for things like bone health. What researchers realized in the last 15 years or so is that low vitamin D levels are also related to a number of other diseases. Low vitamin D has been related to some cancers, cardiovascular disease, diabetes, asthma, autism, depression and other mental health illnesses. The reason researchers started exploring these outcomes is because we realized vitamin D does more in the body than keep bones healthy and help the body use calcium. In fact, all of our cells use vitamin D for some reason. So, when every single cell in the body uses vitamin D, we started thinking that it must be related to something other than just bones.
We started looking at vitamin D in pregnancy because the placenta makes vitamin D and takes it to the unborn baby (the placenta feeds and nourishes the baby and gets rid of waste). Vitamin D helps regulate how the placenta works. Researchers wondered whether vitamin D is related to harmful pregnancy outcomes. We’re particularly concerned about this in Pittsburgh. Many people don’t get enough vitamin D here. This is especially true in the winter and spring months when we don’t see as much sunshine.
We get vitamin D through our food and from sunlight. People get most of their vitamin D just from being in the sunlight for a few minutes. Melanin, which makes people’s skin dark, absorbs vitamin D and acts as a natural sunscreen. It prevents sunlight from getting into the skin and being changed to vitamin D. So, we find that African Americans have a much harder time getting enough vitamin D from sunlight. They need maybe 5 times as much time in the sun as someone with lighter skin would need. You can imagine that getting this much sun can be hard when we spend so much of the winter months indoors. We also see high rates of vitamin D deficiency in Whites in Pittsburgh. But the difference we see between Blacks and Whites is similar to what we see for infant mortality in the county. We saw that vitamin D could be important for pregnancy outcomes. This insight started to make us question whether vitamin D could be adding to racial differences in infant mortality. The goal is to find out whether giving people extra vitamin D will reduce the inequality we see in the county.
CTSI: Would taking prenatal vitamins help with vitamin D deficiency?
Prenatal vitamins contain about 600 international units (IU) of vitamin D. But there’s disagreement about whether that’s enough for most women. We have found that women who take prenatal vitamins about as much vitamin D deficiency as those who don’t. There are limitations with that research, though; we’re basing it on what people tell us. Vitamin D levels are a bit higher in women who take prenatal vitamins but not enough to make a dent in the disparity we see. It seems that higher doses, in the 1,000 to 2,000 IU range, might be what’s needed to raise vitamin D levels in most people and prevent deficiency.
It’s hard because the definition of vitamin D deficiency in adults is controversial. It’s hard to say how much vitamin D women should be taking because we don’t know what the best level is. Some of the work I’m doing now is to relate levels of vitamin D with pregnancy outcomes to determine whether there’s a point at which we see a reduction in risk. If low levels and high levels aren’t good, is there a middle level that’s a sweet spot for most women? Because there hasn’t been much research done, we’re starting from scratch in pregnant women. Right now, it seems that a woman’s vitamin D level when she gets pregnant is most important.
CTSI: Tell us about your pregnancy weight gain research.
It’s similar to the vitamin D work. There are clear racial inequalities in the amount of weight women gain in pregnancy and the weight at which they start pregnancy. African American women have much higher levels of obesity when they start pregnancy. They also tend to gain less weight during pregnancy. In all body-mass index (BMI) groups, it looks as if Black women on average gain less weight than White women. Gaining less weight than is recommended is associated with babies being born too early or too small. These are factors related to infant mortality. Changing a woman’s weight before she gets pregnant is very hard to do. If a woman gets prenatal care, she is getting routine medical contact. She may be more likely at that point to make lifestyle changes because it’s not just for her health—it’s also for her baby’s health. If we could help women gain the appropriate amount of weight, it might reduce some of that disparity in infant mortality.
Starting a pregnancy at too high or too low a BMI is unhealthy. Gaining too little or too much weight is also unhealthy. The reason we’re trying to target weight gain in pregnancy is that once we see women who are pregnant, it’s too late to change their prepregnancy weight. The only thing we can help with at that point is their weight gain during pregnancy. Scientists agree that a woman’s BMI is more important that how much weight she gains in pregnancy. We should be doing more to promote weight loss in women before pregnancy, but that’s proved to be a difficult task. Fifty percent of pregnancies are unplanned, so women usually aren’t thinking about their weight with regard to getting pregnant.
We’re looking at how weight gain may explain infant mortality disparities. Among obese, overweight, normal weight or underweight women, is weight gain adding to infant mortality?
CTSI: How do other things, such as the environment or people’s culture, affect pregnancy weight gain?
So many things can interfere with people having a healthy weight. They include personal choices, as well as the environments and cultures in which we live, how much money we have and how much people know about what’s healthy and what’s not. There are a tremendous numbers of barriers.
Pregnancy could be a time when we can provide resources to women about their weight. It may be a time when we can help stop a weight-gain cycle. In women, we tend to see them gain too much weight in pregnancy, not lose it all after having the baby and then start their next pregnancy at a higher weight. Then, women maybe gain too much weight in another pregnancy and don’t lose it. This cycle puts babies at a higher risk for problems at birth. A woman may start her first pregnancy at a decent weight, but after having three children, she ends up overweight or obese. If we can help her gain an appropriate amount of weight
during pregnancy, that may help stop the cycle. That’s what we want to try to do.
CTSI: What kind of practical advice can you give to women who are concerned about vitamin D or pregnancy weight gain?
Taking a supplement of 1,000 units of vitamin D is safe and won’t hurt most people. If women have easy access to health care, they can ask to have their vitamin D levels checked. It’s safer than spending time out in the sun because we don’t know the amount of sun that is safe.
To control weight gain, women should try eating more fruits and vegetables—fresh, canned, frozen, cooked, whatever—and drink fewer sugary drinks and eat fewer sweets. This would go a long way in promoting health, even without seeing a doctor or getting on a diet plan. Eating fruits and vegetables is better than eating processed food.
Vitamin D is certainly about more than just bones. It can affect pregnancy outcomes in many ways, and we don’t know yet which is most important. So, let’s focus on the things we can control—healthy behaviors and getting the right nutrients.
If you are worried about infant mortality and your risk factors, talk to a health care professional.
Dr. Lisa Bodnar, Ph.D., M.P.H., R.D., is an assistant professor in the University of Pittsburgh School of Public Health’s Department of Epidemiology. She was recently awarded the Young Professional Achievement Award, given by the National Coalition for Excellence in Maternal and Child Health Epidemiology