Q&A: Understanding racial and ethnic differences in fetal growth

Christiana Care Health System played a leading role in a groundbreaking study on racial and ethnic differences in fetal growth, published in the October issue of the American Journal of Obstetrics and Gynecology and sponsored by the U.S. National Institute of Child Health and Human Development. Christiana Care enrolled the most patients in the multi-site study, which concluded that that race and ethnicity play a significant role in birth weights.

The study of 2,334 multi-racial, multi-ethnic women also concluded that current standards, which are more than 30 years old and focused mostly on white women, are outdated. Researchers believe the study will inform new standards that will reduce unnecessary tests.

Anthony Sciscione, D.O., director of the Delaware Center for Maternal & Fetal Medicine of Christiana Care and program director of the Christiana Care OB/GYN Residency Program, was an author of the study.

Q: You have been studying fetal growth for a number of years. What is significant about this latest study?

A: We studied the impact of race and ethnicity on fetal growth in mothers who self identify as Asian, black, Hispanic and white. We learned that there are significant differences in fetal growth among the groups and that as many as 15 percent of non-white fetuses are erroneously classified as too small. The study will inform new guidelines to create a customized approach to fetal growth. Women will get better care that will likely cost less.

Q: What did the study show about the impact of race and ethnicity on fetal growth?

A: There is a huge impact. First of all, we learned that growth patterns are different. The difference in weight is significant in different ethnicities, even though all the mothers in the study had low-risk pregnancies with a single baby. We learned that white and Hispanic babies are on average about one pound bigger than babies who are of Asian or African descent. Boys are bigger than girls across ethnicities.

Q: The study concludes that up to 15 percent of non-white fetuses may be misclassified as too small. What impact does this have on care?

A: Here’s an example: I see a patient who is Asian. She is 5 feet, 2 inches tall, and weighs 110 pounds, and under the current guidelines I have to tell her that her baby is too small and at increased risk. Growth restriction is very serious and could be a sign that the placenta is not doing its job of getting the baby the nutrients he or she needs. We need to perform additional testing, such as ultrasounds twice a week. Plus, the mother suffers the anxiety of worrying that her baby is OK. Our study demonstrates that baby is actually normal weight because we know now that Asian women generally have smaller babies.

Q: Why is it important to study fetal growth patterns?

A:This study will likely have an impact on care worldwide. Establishing more accurate guidelines is great for population health. We also expect fewer unnecessary tests, less anxiety for parents.

Q: What makes Christiana Care Health System an ideal place to study fetal growth?

A: When the National Institutes of Health looks at where to put taxpayers’ money they are very careful about it. We have done multiple NIH trials over the years and have a very long and very good track record. We have a team of research nurses, a statistician and a data manager on staff. We also enrolled 558 patients — more than any of the 12 institutions participating in the study.

There is lots of racial and ethnic diversity in the patients we see at Christiana Care. We have large Hispanic and Asian populations in Delaware. We also have diversity in the resources and vulnerability in our patients. We had a huge impact on a study that will make a big difference in care.

Q: The current standard fetal reference charts date back more than 30 years and focused on white, middle-class mothers. How have things changed since then?

A: Today, we are seeing greater ethnic and racial diversity among our patients. We also are seeing more mothers who are older and more mothers who are obese with comorbidities like diabetes. Guidelines previously were based on live births. Now we are now studying fetal growth through ultrasounds.

Q: Have the results of the study had an impact on the way we care for pregnant women at Christiana Care?

A: Not yet. But it will. Health systems need to develop a universal formula that we can consult when we do ultrasound tests. It will create a new field for ethnicity, which is not currently in the data.

Q: What’s next?

A: We need to take this data and apply it to outcomes. What happens when babies are too big or too small? This will help us to be even better in predicting adverse outcomes. We can be more precise. We can fine tune our care based on ethnicity. We also will be looking for ethnic differences in the fetal growth of twins.