Hair Mercury Levels, Serum n-3 Fatty Acids, and Pregnancy Glucose Outcomes Among Women From a Fertility Center.

Abstract

Mercury (Hg) exposure has been linked to gestational diabetes mellitus, but findings are inconclusive. Fish, the main source of nonoccupational Hg exposure, is also rich in long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs), which may offer metabolic benefits. The joint impact of Hg and n-3 PUFAs on maternal glucose metabolism remains unclear. To examine the association between prepregnancy Hg exposure and glucose metabolism during pregnancy and evaluate whether serum eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) modify this relationship. We included 430 women from the Environment and Reproductive Health Study with prepregnancy hair Hg and mid- to late-pregnancy glucose levels. Of these, 182 had prepregnancy serum EPA and DHA. Generalized linear models were used to assess associations of log-transformed Hg with glucose and impaired glucose tolerance (IGT). Stratified analyses were performed by EPA + DHA levels and prepregnancy body mass inde (BMI). Higher Hg was associated with elevated glucose (per SD: β = 0.09, 95% confidence interval: 0.002-0.19) and 2.05-fold increased odds of IGT (Q4 vs Q1). Similar associations were observed among women with lower circulating EPA + DHA, and stronger associations were seen among those with prepregnancy BMI ≥25 kg/m2. Higher prepregnancy Hg exposure was associated with increased IGT odds, potentially modified by BMI and n-3 PUFA status.