JOHNS HOPKINS (US) — Pregnant women with more exposure to common environmental contaminants carry fetuses that move more frequently and vigorously but sometimes without the heart rate accelerations that indicate the baby is doing well.
Since both fetal motor activity and heart rate provide insight into how a fetus is maturing, results showing that organochlorine chemicals like PCBs and pesticides affect those indicators are of concern.
“There is tremendous interest in how the prenatal period sets the stage for later child development,” says Janet A. DiPietro, professor of population, family, and reproductive health and associate dean for research at the Johns Hopkins Bloomberg School of Public Health.
“These results show that the developing fetus is susceptible to environmental exposures and that we can detect this by measuring fetal neurobehavior. This is yet more evidence for the need to protect the vulnerable developing brain from effects of environmental contaminants both before and after birth.”
DiPietro is a developmental psychologist and lead author of the study, published online in advance of publication in the Journal of Exposure Science and Environmental Epidemiology.
Organochlorines—compounds composed primarily of carbon, hydrogen, and chlorine—don’t break down easily and tend to accumulate in plants, animals, and the environment. They were found in all 50 Baltimore-area pregnant women participating in the study. The chemicals detected included long-banned industrial chemicals called PCBs as well as DDT and other pesticides that also have been illegal to use for more than 30 years.
At 36 weeks of pregnancy, researchers took blood samples from the mothers and measured fetal heart rate and motor activity. The blood was tested for levels of 11 pesticides and 36 PCBs, or polychlorinated biphenyl compounds.
All participants had detectable concentrations of at least one-quarter of the analyzed chemicals, despite the fact that the substances have been out of use for more than three decades.
Higher exposure to seven of 10 organochlorine compounds was associated with more frequent and more vigorous fetal motor activity. Fetal heart rate effects were not consistent across all of the compounds analyzed; when effects were seen, however, higher chemical exposures were associated with reductions in the fetal heart rate accelerations that indicate fetal wellbeing.
“Most studies of environmental contaminants and child development wait until children are much older to evaluate effects of things the mother may have been exposed to during pregnancy,” DiPietro says. “Here we have observed effects in utero.”
Women in the study of higher socioeconomic status had greater concentrations of chemicals than women of lower socioeconomic status.
The Eunice Kennedy Shiver National Institute of Child Health and Human Development and the National Institute for Environmental Health Sciences supported the study.
Source: Johns Hopkins University