Perfluoroalkyl substances during pregnancy and validated preeclampsia among nulliparous women in the Norwegian Mother and Child Cohort Study

Abstract

Perfluoroalkyl substances (PFAS) are persistent and ubiquitous environmental contaminants, and human exposure to these substances may be related to preeclampsia, a common pregnancy complication. Previous studies have found serum concentrations of PFAS to be positively associated with pregnancy-induced hypertension and preeclampsia in a population with high levels of exposure to perfluorooctanoate. Whether this association exists among pregnant women with background levels of PFAS exposure is unknown. Using data from the Norwegian Mother and Child Cohort Study conducted by the Norwegian Institute of Public Health, we carried out a study of nulliparous pregnant women enrolled in 2003-2007 (466 cases, 510 noncases) to estimate associations between PFAS concentrations and an independently validated diagnosis of preeclampsia. We measured levels of 9 PFAS in maternal plasma extracted midpregnancy; statistical analyses were restricted to 7 PFAS that were quantifiable in more than 50% of samples. In proportional hazards models adjusted for maternal age, prepregnancy body mass index (weight (kg)/height (m)(2)), educational level, and smoking status, we observed no strongly positive associations between PFAS levels and preeclampsia. We found an inverse association between preeclampsia and the highest quartile of perfluoroundecanoic acid concentration relative to the lowest quartile (hazard ratio = 0.55, 95% confidence interval: 0.38, 0.81). Overall, our findings do not support an increased risk of preeclampsia among nulliparous Norwegian women with background levels of PFAS exposure.

Keywords: Norwegian Mother and Child Cohort Study; perfluoroalkyl substances; perfluorooctane sulfonate; perfluorooctanoic acid; perfluoroundecanoic acid; preeclampsia.

Figure 1.

Adjusted dose-response relationships between plasma concentrations of perfluoroalkyl substances at midpregnancy and the natural-log–transformed odds ratio for preeclampsia using restricted cubic spline functions among 976 pregnant women enrolled in the Norwegian Mother and Child Cohort Study, 2003–2007. Odds ratios were adjusted for maternal age, prepregnancy body mass index (weight (kg)/height (m)²), education completed, and smoking during pregnancy. Restricted cubic spline functions have 5 knots at the 5th, 25th, 50th, 75th, and 95th percentiles, with the exception of PFDA, which has only 4 knots at the 25th, 50th, 75th, and 95th percentiles. The horizontal line denotes an odds ratio of 1, the vertical line denotes the median of the observed distribution, and observed values are indicated by dots near the x-axis. PFDA, perfluorodecanoic acid; PFHpS, perfluoroheptane sulfonate; PFHxS, perfluorohexane sulfonate; PFNA, perfluorononanoic acid; PFOA, perfluorooctanoic acid; PFOS, perfluorooctane sulfonate; PFUnDA, perfluoroundecanoic acid.