National Health Statistics Reports Number 146 September 10, 2020 Trends and Patterns in Menarche in the United States: 1995 through 2013–2017 By Gladys M. Martinez, Ph.D. Abstract older, have older friends, and be more likely to engage in negative behaviors Objective—This report presents national estimates of age at first menstrual period such as missing school, smoking, and for women aged 15–44 in the United States in 2013–2017 based on data from the drinking (8–11). The younger the age at National Survey of Family Growth (NSFG). Estimates for 2013–2017 are compared first menstrual period and first sexual with those from previous NSFG survey periods (1995, 2002, and 2006–2010). intercourse, the longer the interval Methods—Data for all survey periods analyzed are based on in-person interviews young women will potentially spend at with nationally representative samples of women in the household population aged risk of pregnancy. Differences in age at 15–44 in the United States. For the 2013–2017 survey period, interviews were menarche across population subgroups conducted with 10,590 female respondents aged 15–44. In 2015–2017, the age range may help explain differences in timing of the NSFG included women aged 15–49, but only those aged 15–44 were included of first sexual intercourse and timing of in this analysis. The response rate for the 2013–2017 NSFG was 67.4% for women. first births. The relationship between age Measures of menarche in this report include average age at first menstrual period, at menarche and the timing of first sexual probability of first menstrual period at each age, and the relationship between age at intercourse in the United States has menarche and age at first sexual intercourse. not been widely studied in the past few Results—The median age at menarche decreased from 1995 (12.1) to 2013–2017 decades. Updated trend data help explain (11.9). The cumulative probability of menarche at young ages was higher in more recent patterns of age at menarche 2013–2017 compared with 1995. Differences in age at menarche exist by Hispanic and timing of first sexual intercourse. origin and race, mother’s education, and living arrangement at age 14. A decreasing Studying demographic patterns linear trend in the probability of age at first sexual intercourse by age at menarche was and trends in menarche may also be seen. informative because earlier age at Keywords: age at first menstrual period • first sexual intercourse • coitarche • menarche has been associated with National Survey of Family Growth greater risk of health problems including breast cancer, obesity, diabetes, and liver disease (12–14). In addition, early age Introduction in which females can potentially get at menarche is associated with early age pregnant (1,2). Early menarche has at menopause (15). Reaching menarche This report focuses on age at been associated with earlier age at first earlier than peers has also been associated first menstrual period, also known as sexual intercourse (3–7). One possible with higher risk of depression, eating age at menarche. It is useful to study mechanism in which early menarche disorders, and substance abuse during demographic patterns in menarche may result in earlier age at first sexual adolescence (8,15,16). Some explanations because this biological milestone intercourse is that girls who experience for early onset of menarche include typically marks the start of the period menarche at younger ages may appear genetics and body fat (via production of U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention National Center for Health Statistics NCHS reports can be downloaded from: https://www.cdc.gov/nchs/products/index.htm. Page 2 National Health Statistics Reports Number 146 September 10, 2020 leptin), while others may be related to Measures of menarche 2013–2017 (61.5 million). SAS software, environmental factors that may impact and age at first sexual Version 9.4 (https://www.sas.com), was reproductive hormones, such as growing intercourse used to produce statistics for this report. up in a father-absent home, stepfather Probabilities in this report were presence, and family conflict (8,12,16). This report measures age at calculated using the Kaplan-Meier Since 1982, the National Survey menarche based on a question procedure in the software program of Family Growth (NSFG) has asked administered by interviewers to SUDAAN 11 (https://www.rti.org/ nationally representative samples of respondents asking, “How old were sudaan). The Kaplan-Meier procedure fits women aged 15–44 about their age at you when you had your first menstrual the Kaplan-Meier model, or product-limit menarche. This report presents estimates period?” (MENARCHE). For estimator, to estimate the survival on age at menarche using data from presentation purposes, the data on age at function for a given population (18,19). four of the more recent NSFG survey menarche are shown in five categories: This method takes censored data and the periods (1995, 2002, 2006–2010, and age 10 or under, age 11, age 12, age 13, NSFG’s complex survey design into 2013–2017). This report provides and age 14 or over. Age at first sexual account. The probability of menarche by national estimates on the trends in age intercourse is defined from a recode age represents the expected proportion of at menarche in the United States and (VRY1STAG) based on a question asking women who have had a first period by a differentials in menarche timing by respondents how old they were the first certain age. Probabilities were estimated various characteristics including age, time they had sexual intercourse with a based on retrospective reporting of the mother’s education, and Hispanic origin man. age at first menstrual period and first and race. In addition, this report explores sexual intercourse. In this report, the relationship between age at menarche Selected demographic probabilities are described as and timing of first sexual intercourse. percentages, such as the percentage of variables women who had their first period by age In this report, age at menarche 12. Women whose period had not yet Methods is shown with respect to several key begun were set to missing in this analysis. demographic characteristics including Similar methodology was used to Data source mother’s education, living arrangement calculate the probability of first sexual with parents at age 14, and Hispanic intercourse, stratified by age at menarche. This report uses NSFG data origin and race. Mother’s education is Significant differences between from 1995, 2002, 2006–2010, and included as a proxy for the respondent’s probabilities were tested using the PROC pooled NSFG data from 2013–2017 socioeconomic status when she would SURVIVAL procedure in SUDAAN. (2013–2015 and 2015–2017). The data have had her first menstrual period. Each table in this report includes standard were collected from women in face-to- Living arrangement with parents at age errors as a measure of the precision of face interviews—10,847 in 1995, 7,643 14 is a measure of the family structure each point estimate. in 2002, 12,279 in 2006–2010, and the respondent grew up in during her 10,590 in 2013–2017—representative early teens and has been associated of the U.S. household population aged with timing of menarche. Hispanic Results 15–44. The National Center for Health origin and race are included in this Statistics (NCHS) has been conducting report because previous studies have Trends in mean age at NSFG since 1973 to collect data on found an association between race and fertility, proximate determinants of menarche ethnicity and age at menarche (6,11). The fertility, and reproductive health. NSFG definition of Hispanic origin and race Table 1 shows mean and median is jointly planned and funded by NCHS used in this report considers the reporting age at menarche among women aged and several other U.S. Department of of more than one race, in accordance 15–44 for four time periods from 1995 Health and Human Services programs with the 1997 guidelines from the Office to 2013–2017. There was a decreasing (see Acknowledgments). The response of Management and Budget (18), and linear trend in the median age at rate for women aged 15–44 in the NSFG while not shown separately, data from menarche in the United States from was 78.5% in 1995, 80% in 2002, 78% respondents reporting more than one race 1995 to 2013–2017. The median age at in 2006–2010, and 67.4% in 2013–2017. are included in the total. menarche decreased from 12.1 in 1995 More details on the sample design, to 11.9 in 2013–2017. In 2013–2017, fieldwork procedures, and variance one-half of women reached menarche by estimation for the 2013–2017 NSFG Statistical analysis age 11 years and 10 months. There was were previously published (https://www. All estimates in this report are no significant difference in mean age at cdc.gov/nchs/nsfg/nsfg_2015_2017_puf. weighted to represent women aged 15–44 menarche from 1995 through 2013–2017. htm#design). in the household population of the United States in 1995 (60.2 million), 2002 (61.6 million), and at the midpoint of 2006–2010 (61.7 million) and National Health Statistics Reports Number 146 September 10, 2020 Page 3 Cumulative probability of in the older ages. Non-Hispanic black parents at age 14, 8% had reached menarche by age women were not significantly different menarche by age 10, 24% by age 11, than Hispanic or non-Hispanic white and 52% by age 12. Among women who Table 2 shows the cumulative women in their probability of menarche lived with their mother and stepfather at probability of menarche by age and at each age.