Low birth weight, preeclampsia, and disrupted gestational thyroid hormone are three of the most common complications during pregnancy that pose serious and sometimes lethal maternal and fetal risks. An increasing number of studies are identifying a connection between the complications and prenatal exposure to chemical compounds found in everyday products.
Liping Feng, MD, is an associate professor of obstetrics and gynecology and Duke Global Health Institute member researching the mechanisms of pregnancy complications associated with the placenta. In this Q&A, she discusses her research on environmental risk factors for pregnancy complications.
Question: What is the current state of maternal health research into environmental exposure?
Feng: We’ve long known that the short- and long-term health of babies is imprinted during the critical nine months of pregnancy. Maternal age, stress levels, and genetic background are commonly known risk factors, but the literature hasn’t historically considered environmental exposure. In our industrialized world we are all exposed to around 80,000 compounds daily, and we don’t yet know enough about the health impact of that exposure during pregnancy. Through our research, we hope to raise awareness of these potentially harmful substances to help mitigate the occurrence of complications such as preeclampsia and low birth weight. We need more expertise in this field, and I’m proud to contribute to this aspect of health care.
Question: What are the primary chemical substances targeted in your research?
Feng: The emerging perfluoroalkyl and polyfluoroalkyl substances (PFAS) are the main focus of my research. PFAS are man-made chemicals used in a wide array of products, such as carpets, upholstery, nonstick cookware, food packaging, and firefighting foam. Over the past 10 years, some of those “legacy” PFAS, such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), were found to be toxic and were replaced with compounds such as perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), perfluorobutyrate (PFBA), and GenX. PFAS can be detected above the minimum reporting levels in drinking water samples across the United States. There are high levels of GenX contamination in the Cape Fear River in North Carolina, which is a source of drinking water for more than 250,000 people in the Wilmington area. Recently, my research team in collaboration with Dr. Heather Stapleton, an associate professor in Nicholas School of the Environment at Duke University, discovered high levels of PFAS contamination in Haw River, North Carolina.
Question: What are your main findings?
Feng: Our studies, including a study published in Environment International and a 2019 study published in Environmental Health, have consistently found that those “replacement” compounds are indeed harmful to mothers and fetuses. They are associated with preeclampsia and overall hypertensive disorders of pregnancy, as well as interruption to thyroid hormone levels. Preeclampsia causes maternal and fetal death and low birth weight; disrupted thyroid hormones impact babies’ short- and long-term health, particularly in brain development, as the disruption can cause low IQ, ADHD, and autism. Furthermore, my lab found that PFBS interrupts placental development and functions including the productions of hormone growth factors and thyroid hormone metabolism using in vitro and in vivo models. These results provide the underlyng mechanisms for the associations between prenatal PFBS exposure and adverse birth outcomes.
Question: What advice do you have for providers in caring for their patients who are pregnant or want to become pregnant?
Feng: Providers should include environmental exposure in discussions about risk factors for pregnancy complications. Ask patients about their occupation, as there are a number of occupations, such as firefighting, that may expose them to harmful chemicals. Ask about their home environment and residency area, as contamination from heavy metals is often found in low-income areas and PFAS contamination in certain areas. The point is to make patients aware of their exposures and help them find solutions to limit them during pregnancy. For example, Dr. Stapleton’s group recently identified the most effective method (reverse osmosis) to filter out PFAS from drinking water. We all may think we live in a clean world and we don’t often consider that we’re exposing ourselves to all of these chemicals every day, but it’s very real. Through our continuing research my hope is that we can identify biomarkers that will help us find solutions for patients with high exposure levels and that we can help bring more healthy babies into the world.