(HealthDay News) – Maternal exposure to bisphenol A (BPA) during pregnancy is related to reduced free thyroxine (T4) in the mother and lower thyroid-stimulating hormone (TSH) in male neonates, according to research published online Oct 4 in Environmental Health Perspectives.

Jonathan Chevrier, PhD, of the Center for Environmental Research and Children’s Health at the University of California in Berkeley, and colleagues conducted a study to measure BPA concentrations in urine samples of 476 pregnant women during the first and second halves of their pregnancy to examine whether exposure to BPA impacts the thyroid function of women or their neonates.

The researchers identified a significant association between the two BPA measurements and maternal thyroid hormone levels. The measurement taken closest in time to the thyroid hormone measurement correlated significantly with a reduction in total T4. For boys, but not girls, the average maternal BPA concentrations correlated with reduced TSH. The link was more robust when BPA was assessed in the third trimester, and was reduced with the time between BPA and thyroid hormone measurements in boys.

“In summary, we report an inverse relation between BPA concentration in maternal urine and maternal serum total T4 during pregnancy,” the authors write. “Although we cannot rule out that average BPA concentrations during pregnancy may be relevant, the association of maternal BPA and total T4 was stronger when they were measured closer together relative to further apart in time, suggesting a transient effect of BPA.”

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