A study conducted by researchers based at the Johns Hopkins Bloomberg School of Public Health has shown that when pregnant mothers-to-be are exposed to high levels of common environmental toxins it stimulates more frequent energetic spurts of motor activity in the developing fetus. Some chemical toxins are also linked to fewer changes in fetal heart rate, which typically correspond to fetal activity. The study, which was recently published in the Journal of Exposure Science and Environmental Epidemiology, found traces of organochlorines, including PCBs, DDT, and other toxic pesticide chemicals that were banned over 30 years ago and are no longer in use, at detectable levels in all the pregnant women that took part in the study.
“Both fetal motor activity and heart rate reveal how the fetus is maturing and give us a way to evaluate how exposures may be affecting the developing nervous system. 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; here we have observed effects in utero,” explains Janet DiPietro, Associate Dean for Research at the Bloomberg School of Public Health, and lead author of the study.
DiPietro and her research team monitored a sample of fifty pregnant women from both low- and high-income suburbs in the Baltimore area. Fetal heart rate as well as motor activity were measured at week 36 of the pregnancy, and blood samples were taken from the mothers. The latter were screened for 11 different pesticides and 36 different polychlorinated biphenyl compounds (PCBs).
The results showed that all the study participants had detectable levels of at least 25% of the toxins they were tested for, even though they were banned more than thirty years ago. Women from higher-income groups within the study had higher levels of chemicals present in their blood than women from low-income areas.
The effect on fetal heart rates were not consistent for all the chemicals tested, but when effects were observed they were typically associated with reduced fetal heart rate accelerations – indicating fetal well being. However, links between toxin concentrations and fetal motor activity were more robust, showing higher levels of consistency – high levels of 7 of the 10 organochlorine compounds tested for, including DDT, hexachlorobenzene, and a number of PCB compounds, showed a positive correlation with more regular and more energetic fetal motor activity.
“There is tremendous interest in how the prenatal period sets the stage for later child development. 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,” said DiPietro.
To minimize risk of exposure to environmental toxins, especially pesticides, it is advisable to thoroughly wash fruit and vegetables, or better still remove the peels, before consuming. Also, use a good quality drinking water filter to remove pesticides and other chemical toxins from drinking water and from water used to prepare food.
Janet A DiPietro, Meghan F Davis, Kathleen A Costigan, Dana Boyd Barr. Fetal heart rate and motor activity associations with maternal organochlorine levels: results of an exploratory study. Journal of Exposure Science and Environmental Epidemiology, 2013; DOI:10.1038/jes.2013.19 CT92YQ6ES7ZB