Short communicationGirl or boy? Prenatal lead, cadmium and mercury exposure and the secondary sex ratio in the ALSPAC study

•The secondary sex ratio is declining in many countries.•We evaluated the effect of prenatal exposure to heavy metals.•There were no associations between heavy metals and the secondary sex ratio.•Further work should be done in large cohorts in other countries.

The aim of this study was to evaluate the effect of prenatal exposure to lead, cadmium and mercury levels on the secondary sex ratio. Whole blood samples were collected from pregnant women enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) study at a median gestational age of 11 weeks and were analyzed for lead, cadmium and mercury. Regression analysis was used to identify associations between maternal lead, cadmium and mercury levels and the secondary sex ratio with adjustment for confounders. There was no evidence for associations between maternal lead, cadmium or mercury levels and the secondary sex ratio in this sample. It appears unlikely that alterations in the secondary sex ratio are influenced by exposure to heavy metals, but further work should be done in large cohorts in other countries to confirm these findings.