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

Purpose: Early 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. Methods: Using 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. Results: Younger 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. P-trend < .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, P-trend < .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, P-trend < .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, P-trend < .006). Conclusions: Age at menarche and menstrual cycle regularity are significantly influenced by several individual, environmental and lifestyle factors. (C) 2012 Elsevier Inc. All rights reserved.