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Appiah D, Nwabuo CC, Ebong IA, Wellons MF, Winters SJ. Trends in Age at Natural Menopause and Reproductive Life Span Among US Women, 1959-2018. JAMA. 2021;325(13):1328–1330. doi:10.1001/jama.2021.0278
Menopause, the permanent cessation of menstruation for more than 12 consecutive months resulting from the loss of ovarian function, marks the end of a woman’s reproductive cycle.1 Trends of increasing age at natural menopause have been reported worldwide.2 Understanding changes in the timing of age at natural menopause and length of reproductive life span (age at menopause minus age at menarche) and their associated factors are important because they influence multiple health conditions.1 This study investigated 60-year trends in age at natural menopause and reproductive life span as well as associated factors among US women.
Data were from successive surveys spanning the National Health Examination Survey I (NHES I; 1959-1962) through the National Health and Nutrition Examination Survey (NHANES) for 2017-2018. Response rates ranged from 87% for the NHES I to 49% for NHANES 2017-2018. These surveys used similar standardized protocols to obtain nationally representative estimates for the US noninstitutionalized civilian population and were approved by the National Center for Health Statistics Research Ethics Review Board.3 All participants provided written informed consent. Ages at menarche and menopause were self-reported. All women aged 40 to 74 years with natural menopause and no missing age at menopause were included in this analysis. Women with the following characteristics were excluded: menopause due to medical treatment or other reasons, age at natural menopause before age 40 years or after age 62 years (because pathologic conditions may have influenced the occurrence of menopause at such ages),4 and reporting a race/ethnicity other than Black, White, or Hispanic. Trends in age at natural menopause and reproductive life span over time were examined using linear regression, while ordinal logistic regression was used to evaluate factors (Table 1) associated with higher age at menopause and longer reproductive life span. All models accounted for the complex design and sampling weights of the surveys using SAS version 9.4 (SAS Institute Inc). Consecutive 2-year surveys conducted after 1999 were grouped into 4-year intervals to produce statistically reliable estimates. A 2-tailed P < .05 indicates statistical significance.
Of 9428 women aged 40 to 74 years at the time of the survey with natural menopause and without missing age at menopause, 1655 were excluded. Table 1 shows the characteristics of the 7773 included women. Overall, from 1959-1962 to 2015-2018, the mean age at natural menopause increased from 48.4 years to 49.9 years (P < .001 for trend). Over this interval, the mean reproductive life span increased from 35.0 years to 37.1 years (P < .001 for trend), while the mean age at menarche declined from 13.5 years to 12.7 years (P < .001 for trend). In adjusted models, Black or Hispanic race/ethnicity, poverty, current and former smoking status, and hormone therapy use were associated with earlier age at natural menopause and shorter reproductive life span, while greater years of education and oral contraceptive use were associated with later age at natural menopause and longer reproductive life span (Table 2).
Over the past 6 decades, the mean age at natural menopause increased by 1.5 years and the mean reproductive life span by 2.1 years.
The increase in reproductive life span was driven both by increasing age at natural menopause and earlier age at menarche. Sociodemographic, lifestyle, and behavior factors were significantly associated with age at natural menopause and reproductive life span. Additional potential contributing factors may include improved access to health care, nutrition, and environmental factors.1,5
Limitations of this study include its repeated cross-sectional design, relatively small sample size, and potential recall bias in age at menarche and menopause, although moderate reliability in the recall of these events after several years has been reported.6
Available evidence links later age at natural menopause with reduced all-cause and cardiovascular mortality but increased risk of breast, endometrial, and ovarian cancers.1 Whether the 1.5-year increase in age at natural menopause over a 60-year time span has clinical significance for women’s health apart from reproduction is unknown.
Corresponding Author: Duke Appiah, PhD, MPH, Department of Public Health, Texas Tech University Health Sciences Center, 3601 Fourth St, Stop 9430, Lubbock, TX 79430 (firstname.lastname@example.org).
Accepted for Publication: January 10, 2021.
Author Contributions: Dr Appiah had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Appiah, Nwabuo, Ebong, Wellons.
Acquisition, analysis, or interpretation of data: Appiah, Nwabuo, Ebong, Winters.
Drafting of the manuscript: Appiah.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Appiah, Nwabuo.
Administrative, technical, or material support: Wellons.
Conflict of Interest Disclosures: None reported.
Disclaimer: The National Health and Nutrition Examination Survey is conducted by the National Center for Health Statistics, Centers for Disease Control and Prevention (CDC). The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the CDC.