14. Maternal exposure to perfluorinated chemicals and reduced fecundity: the MIREC Study (lay summary)

Vélez MP, Arbuckle TE, Fraser WD. Human Reproduction. 2015;30(3):701-9. doi: 10.1093/humrep/deu350

This paper examines maternal exposures to specific perfluorinated chemicals (PFCs) – perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorohexane sulfonate (PFHxS) – and their potential effect on female fertility. PFCs are a group of chemicals used in various industrial and commercial products, and there may be concern about their potential effect on fertility. Some recent research suggests an association between increasing levels of PFCs and reduced fertility, while other studies have found no such association.

This PFC and fertility study used data from the MIREC Study (Maternal-Infant Research on Environmental Chemicals) a cohort of 2,001 women recruited in the first trimester of pregnancy in 10 cities across Canada between 2008 and 2011. A total of 1,743 pregnant women from this cohort were included in the PFC-fertility analyses. The researchers administered a questionnaire, asking the study participants how many months of unprotected intercourse it took to become pregnant in their current pregnancy – i.e., fertility was measured by “time-to-pregnancy.” Infertility, on the other hand, was defined as more than 12 months of trying to become pregnant, or infertility treatment for the current pregnancy. Maternal blood samples were analyzed for levels of three common PFCs: PFOA, PFOS, and PFHxS, and the results were adjusted for potential confounding factors such as age, socio-economic status, and body mass index.

PFC levels were lower than those reported in previous studies, but even at these lower levels, PFOA and PFHxS were found to be associated with reduced fertility – i.e., an increase in the number of months to become pregnant. Furthermore, the odds of infertility increased as the blood levels of PFOA and PFHxS increased. No significant associations were found for PFOS.

However, there were several limitations to this study. Specifically, other factors that can affect fertility were not addressed: it is possible that women having the highest PFC levels were excluded from the study if there is indeed a causal link between these levels and infertility. Also, the health status and PFC levels in the male partners were not assessed, nor were semen quality, menstrual cycle characteristics of the women, or the frequency of intercourse. Nonetheless, these study results suggest that maternal exposure to PFOA and PFHxS, even at lower levels than previously reported, may reduce fertility.