Mother, Child, PCBs
Expectant mothers often experience equal parts joy and anxiety as they count down the months to baby’s arrival. The concern: Are they doing everything possible during pregnancy to ensure the long-term health of their child?
A researcher and an expectant mom in 2003, Tatiana Prowell volunteered for a study on pregnant women, and relished the opportunity to see her baby developing so much that she signed up twice more, during two subsequent pregnancies.
She continues to stay involved through follow-up questionnaires about her three children’s development and personalities. “Those are the things I’m going to be most interested in long term,” she says. “The relationship between something I did or didn’t do, or something that happened or didn’t happen during my pregnancy, and will that affect my kids’ outcomes long term? It’s so fascinating.”
Those studies were among an ongoing series that Janet DiPietro, PhD, associate dean for Research at the Bloomberg School, and her team have been carrying out since 1991. She was then one of the first researchers to simultaneously measure both maternal and fetal indicators like heart rate and motor activity. Interested in documenting normal development before birth, DiPietro has measured the same core indicators on 11 cohorts of 950 total mother-fetus pairs, and continues to follow the development of the resulting children. That data set—unique in the field—allows DiPietro’s team to explore the real-time interactions between the “intrauterine milieu” and the fetuses’ activities, and track later development against that early information.
Fetuses whose mothers have higher levels of PCBs, DDT and other organochlorines have more frequent and vigorous movements. Exposure to such chemicals might alter “the trajectory of the child’s development.”
In a February 2013 article in the Journal of Exposure Science and Environmental Epidemiology, DiPietro unearthed some fascinating (and worrisome) findings about chemicals like PCBs and DDT, which have been banned for more than 30 years but do not break down easily. They therefore can accumulate in fat in our bodies mainly through pesticide residues in food. The study shows a link between pregnant women’s higher levels of these organochlorines and more frequent and vigorous movements in the fetuses they carry. At the same time, the accompanying heart rate acceleration typically indicating the baby is doing well is not always present.
What that increased activity means is hard to say. No one knows how much fetal movement is optimum, and there is wide variation between fetuses. So movement is viewed more as part of a developing temperament. While one study has suggested a link with attention deficit hyperactivity disorder, DiPietro cautions that too little information is available to make this leap. However, since motor activity and heart rate offer insight into a fetus’s development, the findings are concerning,” she says.
“All I can say from the study is that motor activity is affected,” DiPietro says. “And since spontaneous motor activity is generated by the brain, that means the nervous system and brain are affected by exposures. What the implications are after birth is really unknown.”
She adds: “I think it might indicate that it alters the trajectory of development for that child.”
In DiPietro’s research space in the Johns Hopkins Hospital, the standard protocol begins with a brief ultrasound, but instead of focusing on anatomy, the team looks for fetal behaviors—sucking, for example—as well as measuring amniotic fluid and fetal heart rate. Meanwhile, the mom’s heart rate and skin conductance (an indicator of emotionality) are also evaluated.
In the recent pilot study, DiPietro’s team found organochlorines in all 50 Baltimore- area women participating. There were slightly higher levels among women of higher socio-economic status. That the levels were associated with fetal movement and heart rate does not indicate the need for any specific medical intervention, DiPietro says, but does suggest a public health application of her body of work on normative fetal behavior.
“My feeling is the fetus is the canary in the coal mine, and if something is altering fetal behavior, the chances it’s doing so by affecting the nervous system are pretty high, and we should pay attention,” DiPietro says.
DiPietro’s research is widely noted for the way it frames the important questions in developmental and health research, and for providing quantitative insight into the fetal environment and which components affect developmental trajectories, says William Fifer, PhD, professor of Psychiatry and Pediatrics at Columbia University and associate director of the Sackler Institute of Developmental Psychobiology.
This study, he adds, provides a crucial window into the developing brain. “These results are going to help us focus our investigative lenses in important new directions … to help tease apart exactly how exposure is affecting brain behavior development,” Fifer says.
For DiPietro, the next step is a larger version of the same study, which will allow her team to examine different mixtures of contaminants and explore the interactions between them.