Lead is a persistent, toxic substance and its exposure has been associated with later puberty onset and maturity. Current literature on the role of lead on puberty timing of girls is limited and understanding of mechanisms unclear.

To explore the association of gestational lead concentrations with timing of menarche.

The study population was the Avon Longitudinal Study of Parents and Children. Repeated assessments of menarcheal status were obtained from girls from age 8 through 17. Whole blood samples were obtained in 1991-92 from mothers during the girls’ gestation and lead levels measured using cell mass spectrometry. Potential confounders or effect modifiers considered include: mothers’ education, age at delivery, and smoking during gestation; parity; and the girls’ weight status at age 7. Classification of body mass index (BMI) into healthy or overweight/obese weight status was done using the BMI cutoffs for children developed by the International Obesity Task Force. Data analyses involved 918 enrollees of white race. Parametric survival modeling was used to estimate median ages of entry into menarche in months. Results. The median age of menarche attainment was 150 months (12.5 years). Median lead concentration was 3.4 µg/dL (interquartile range 2.7-4.3 µg/dL). Lead exposure was associated with timing of menarche in models adjusted for the mothers’ age at delivery, smoking, and parity after stratification by the girls’ weight status. Direction of the associations differed by weight status. On average, the estimated median age of entry into menarche per 1 µg/dL increase in lead concentrations in healthy weight girls occurred 0.7 months later (95% confidence interval [95%CI]: 0.1, 1.3) and in obese/overweight girls occurred -1.9 months earlier (95%CI: -3.6, -0.1).

The influence of lead exposure on the timing of puberty may be mediated through alterations in growth.