Exposure to phytoestrogens in utero and age at menarche in a contemporary British cohort

Abstract Phytoestrogens are estrogenic compounds that occur naturally in plants. Phytoestrogens can cross the placenta, and animal studies have found associations between in utero exposure to phytoestrogens and markers of early puberty. We investigated the association between in utero exposure to phytoestrogens and early menarche (defined as O -desmethylangolensin ( O -DMA) 13.0 (4.4–34.5), enterodiol 76.1 (39.1–135.8), and enterolactone 911.7 (448.1–1558.0). In analyses comparing those in the highest tertile relative to those in the lowest tertile of in utero phytoestrogen exposure, higher enterodiol levels were inversely associated with early menarche (odds ratio (OR)=0.47; 95% confidence interval (CI): 0.26–0.83), while higher O -DMA levels were associated with early menarche (OR=1.89; 95% CI: 1.04–3.42). These findings suggest that in utero exposure to phytoestrogens may be associated with earlier age at menarche, though the direction of association differs across phytoestrogens.