Determinants of age at menarche and time to menstrual cycle regularity in the French E3N cohort

PurposeEarly menarche has been associated with a greater risk of several major chronic diseases. Although largely genetically determined, age at menarche also has been related to environmental and lifestyle factors.MethodsUsing linear regression models, we explored simultaneously several pre- and postnatal factors as potential determinants of age at menarche and time to menstrual cycle regularity in 96,493 women participating, since 1990, in the French E3N prospective cohort.ResultsYounger age at recruitment, greater father's income index, urban birth place, greater birth length, and larger body silhouette during childhood were associated with an earlier age at menarche (from −1.3 to −4.6 months, Ptrend < .0001) whereas greater family size, food deprivation during childhood, and greater birth weight resulted in a delayed menarche (from +1.5 months to +5.3 months, Ptrend < .0001). Father's income index, urban birth place, and prematurity predicted a shorter time to menstrual cycle regularity (from −1.1 to −1.9 months, Ptrend < .04), whereas birth cohort, larger body silhouette at menarche, and childhood exposure to passive smoking were associated with a longer time to menstrual cycle regularity (from +1.1 months to +8.6 months, Ptrend < .006).ConclusionsAge at menarche and menstrual cycle regularity are significantly influenced by several individual, environmental and lifestyle factors.