Sexual Orientation and Age at Menarche in Three U.S. Longitudinal Cohorts.

Abstract Purpose The aim of this study is to examine age at menarche across sexual orientation groups. Methods Data were obtained from 131,090 female participants, born 1947–2001, in 3 longitudinal studies—the Growing Up Today Study and Nurses’ Health Study 2 and 3. We estimated the association between sexual orientation and age at menarche using regression models adjusted for age, race/ethnicity, birthweight, height, and body mass index. Results Compared to heterosexual participants, sexual minorities were younger at menarche. Sexual minorities were more likely to have early menarche (≤11 years) and less likely to have late menarche (≥14 years) compared to heterosexual girls. As an example of this pattern, Nurses’ Health Study 3 bisexual participants were >30% more likely than heterosexuals to have early versus average menarche (odds ratio 1.37, 95% confidence interval 1.09–1.72). Conclusion Sexual minority girls have a younger age at menarche than heterosexual girls and may benefit from screening for adverse outcomes associated with early menarche.