21. Maternal and neonatal levels of perfluoroalkyl substances in relation to gestational weight gain (lay summary)

Ashley-Martin J, Dodds L, Arbuckle TE, Morisset AS, Fisher M, Bouchard MF, Shapiro GD, Ettinger AS, Monnier P, Dallaire R, Taback S, Fraser WD. Int J Environ Res Public Health. 2016 Jan 20;13(1). pii: E146. doi: 10.3390/ijerph13010146

Perfluoroalkyl substances (PFASs) are widely available, persistent chemicals with water and oil resistant properties. They are used in the production of common household and consumer goods, including cookware, clothing, and food packaging. Despite the fact that common PFASs, such as perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS), and perfluorohexanesulfanoate (PFHxS) are being phased out, human exposure remains widespread.

Exposure to environmental chemicals during pregnancy is of special concern, as pregnancy is a time of greater susceptibility to potential harmful effects. It is known that PFASs are able to cross the placenta, thus directly exposing the fetus. Prenatal exposure to PFOA, for example, has been associated with reduced fetal growth. The relationship between prenatal exposures to these chemicals and weight gain during pregnancy (referred to as gestational weight gain (GWG)) has received limited attention.

GWG is an important predictor of a variety of health outcomes in the mother, fetus, and newborn infant, including retaining weight after pregnancy and higher infant weight at birth. However, little is known about possible associations between exposure to various chemicals and GWG, with a few studies suggesting a possible link between GWG and environmental chemical burden in the newborn infant. (Chemical burden is the total amount of a particular substance in the body. Some substances build up in the body because they are stored in fat or bone or because they leave the body very slowly). To shed some light on this question, the current study explored potential associations between first trimester blood plasma levels of PFAS (i.e., PFOA, PFOS, and PFHxS) in pregnant women and GWG, and also whether GWG was related to PFAS levels in the umbilical cord blood of their newborn infants.

This study analyzed data and blood samples collected in the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a trans-Canada study of 2001 pregnant women recruited from 10 Canadian cities between 2008 and 2011. Researchers used data from a sub-sample of 1,723 women in the MIREC Study who had a singleton, live term birth, delivered at >34 weeks gestation, had no missing data on gestational weight gain, and had first trimester maternal PFAS data; and 1,301 participants who had umbilical cord blood data. They then examined associations between (1) maternal PFAS levels and GWG and (2) GWG and umbilical cord blood PFAS levels.

PFAS levels in the MIREC study women were comparable to those in a representative sample of Canadian women ages 20–39. This study found that higher levels of PFOS in maternal blood were associated with larger weight gains during pregnancy (GWG), and increases in GWG were associated with elevated umbilical cord blood levels of PFOA and PFOS. No significant associations were found between GWG and PFHxS.

This study raises interesting questions about the complex pathways between maternal and neonatal chemical burdens and GWG that warrant further research. In particular, the observed associations between higher GWG and elevated PFOA and PFOS umbilical cord blood levels suggest that biological changes in women during pregnancy such as higher GWG may influence the levels of these chemicals in their newborn infants.