Trends and Patterns in Menarche in the United States: 1995 through 2013-2017.

Objective-This report presents national estimates of age at first menstrual period for women aged 15-44 in the United States in 2013-2017 based on data from the National Survey of Family Growth (NSFG). Estimates for 2013-2017 are compared with those from previous NSFG survey periods (1995, 2002, and 2006-2010). Methods-Data for all survey periods analyzed are based on in-person interviews with nationally representative samples of women in the household population aged 15-44 in the United States. For the 2013-2017 survey period, interviews were conducted with 10,590 female respondents aged 15-44. In 2015-2017, the age range of the NSFG included women aged 15-49, but only those aged 15-44 were included in this analysis. The response rate for the 2013-2017 NSFG was 67.4% for women. Measures of menarche in this report include average age at first menstrual period, probability of first menstrual period at each age, and the relationship between age at menarche and age at first sexual intercourse. Results-The median age at menarche decreased from 1995 (12.1) to 2013-2017 (11.9). The cumulative probability of menarche at young ages was higher in 2013-2017 compared with 1995. Differences in age at menarche exist by Hispanic origin and race, mother's education, and living arrangement at age 14. A decreasing linear trend in the probability of age at first sexual intercourse by age at menarche was seen.