63. Association Between Gestational Urinary BPA Concentrations and Adiposity in Young Children: the MIREC Study (lay summary)

Braun JM, Li N, Arbuckle TE, Dodds L, Massarelli I, Fraser WD, Lanphear BP, Muckle G. Environmental Research.  2019 Feb 26;172:454-461. doi: 10.1016/j.envres.2019.02.038

Exposure to some environmental chemicals during pregnancy may be associated with the development of childhood obesity. Research suggests that Bisphenol A, also known as BPA, might be one of these chemicals. This research also suggests that BPA might have a different impact on obesity for boys versus girls. BPA is a chemical that is used in many plastic consumer products and in food packaging. Diet is the most common source of exposure to BPA, and most Canadians are exposed to small amounts of BPA.

To address this issue, researchers used data from the MIREC study. They examined the potential relation between a mother’s exposure to BPA during pregnancy and measures of obesity in their children around age 3 years. They also examined whether this relation was different for boys and girls. Urine samples were collected from 719 women during the first trimester of pregnancy and were analyzed for BPA. Several indicators of obesity were measured in their MIREC children.

Overall, BPA exposure during pregnancy was associated with slightly higher measures of obesity in girls, but not in boys. Each 2-fold increase in BPA concentration in mothers’ urine was associated with a 0.2 cm increase in waist circumference and 0.15 mm increase in subscapular (below shoulder blade) skinfolds in girls.

One of the reasons for the difference between girls and boys could be that BPA might affect some hormones, like androgens, during pregnancy. These hormones are typically higher in boys.

In this sample of Canadian women and their children, higher exposure to BPA during pregnancy was associated with small increases in some measures of obesity in girls, but not boys, around age 3. A limitation of this study was that only one urine sample was analysed for each pregnancy.  Concentrations of BPA are known to fluctuate depending on when the urine sample is collected.  Therefore, future studies should analyse more urine samples per woman to obtain a better estimate of her exposure during pregnancy.

In conclusion, this study provides some support for the theory that exposure to environmental chemicals during pregnancy could increase the risk of childhood obesity.