Has age at menarche changed? Results from the National Health and Nutrition Examination Survey (NHANES) 1999-2004

Abstract

Purpose: To examine self-reported age at menarche in U.S. adults and the associations between age at menarche and race/ethnicity.

Methods: Data from 1999-2004 National Health and Nutrition Examination Survey (NHANES) for 6788 females 20 years and over were analyzed. Self-reported age at first menses (in years) by birth year groups is reported overall and for Mexican Americans, non-Hispanic whites, and non-Hispanic blacks.

Results: Mean age at menarche in the United States declined over time from 13.3 years (95% CI: 13.2-13.5) in the oldest age group, those born prior to 1920, to 12.4 years (95% C.I. 12.2-12.5 years) in the youngest group, born between 1980 and 1984. Declines in age at menarche were observed for all race/ethnicity groups. Non-Hispanic black females had the largest decline in mean age at menarche from 13.6 years (95% CI: 13.1-14.1) in women born prior to 1920, to 12.2 years (95% CI: 11.8-12.6) in the 1980-84 birth cohort. Mean age at menarche among non-Hispanic white females declined from 13.3 years (13.1-13.6) in the pre-1920 birth cohort to 12.5 years (12.3-12.8) in the 1980-84 birth cohort.

Conclusions: Significant declines in the mean age of menarche for U.S. females occurred overall and for all race/ethnic groups examined. Mean age of menarche declined by .9 year overall in women born before 1920 compared to women born in 1980-84; the declines in the mean age at menarche ranged from .7 to 1.4 years depending on the race/ethnicity group.