Abstract
This national survey study uses the National Health and Nutrition Examination Survey (NHANES) to describe trends in age at natural menopause, age at menarche, and reproductive life span, and variables associated with shorter and longer spans, among US women between 1959-1962 and 2015-2018.
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.
Methods
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.
Table 1. Characteristics of US Women Aged 40 to 74 Years Who Reported Having Natural Menopause, 1959-2018a.
| Characteristics | 1959-1962 | 1971-1975 | 1988-1994 | 1999-2002 | 2003-2006 | 2007-2010 | 2011-2014 | 2015-2018 |
|---|---|---|---|---|---|---|---|---|
| Unweighted No. | 708 | 1271 | 1349 | 730 | 717 | 1065 | 960 | 973 |
| Age, y | ||||||||
| 40-49 | 24.1 (20.3-27.9) | 21.4 (18.4-24.4) | 13.4 (10.8-16.0) | 23.9 (18.5-29.3) | 21.0 (17.1-24.9) | 18.4 (15.4-21.5) | 15.3 (12.4-18.1) | 15.5 (12.1-19.0) |
| 50-64 | 42.0 (38.7-45.3) | 45.6 (41.3-49.9) | 45.6 (42.2-49.0) | 37.9 (33.2-42.6) | 44.1 (40.8-47.3) | 48.5 (44.3-52.8) | 52.6 (48.3-56.8) | 47.9 (43.4-52.3) |
| ≥65 | 33.9 (29.9-37.9) | 33.0 (28.9-37.0) | 40.9 (37.4-44.5) | 38.2 (34.1-42.3) | 34.9 (31.7-38.1) | 33.0 (28.9-37.2) | 32.1 (28.2-36.1) | 36.6 (32.9-40.3) |
| Race/ethnicityb | ||||||||
| White | 92.5 (89.9-95.2) | 89.2 (86.5-92.0) | 82.7 (78.6-86.7) | 77.8 (72.5-83.1) | 82.7 (77.9-87.6) | 79.6 (74.8-84.3) | 78.4 (73.3-83.5) | 77.5 (72.8-82.3) |
| Black | 7.5 (4.8-10.1) | 9.3 (6.9-11.8) | 8.7 (6.4-11.0) | 9.0 (6.0-12.0) | 8.4 (5.5-11.4) | 10.4 (7.8-13.0) | 9.8 (7.0-12.5) | 9.8 (7.0-12.7) |
| Hispanic | 1.4 (0.2-2.7) | 8.6 (5.4-11.7) | 13.2 (8.2-18.1) | 8.9 (5.7-12.0) | 10.1 (6.4-13.8) | 11.8 (8.3-15.3) | 12.6 (9.3-16.0) | |
| Non–US born | 7.6 (5.6-9.6) | 13.6 (10.0-17.3) | 13.5 (9.3-17.7) | 9.7 (6.7-12.8) | 11.6 (7.8-15.5) | 12.5 (9.6-15.3) | 14.2 (10.5-17.9) | |
| Greater than a high-school education | 15.4 (10.8-20.0) | 18.4 (15.5-21.4) | 29.8 (25.7-34.0) | 48.9 (44.0-53.8) | 57.1 (51.7-62.6) | 59.0 (54.0-64.0) | 63.7 (57.2-70.2) | 64.3 (59.7-68.8) |
| Poverty (poverty income ratio <1.3)c | 28.9 (23.4-34.3) | 24.5 (20.9-28.1) | 24.4 (20.6-28.2) | 28.7 (23.6-33.9) | 19.8 (15.5-24.0) | 21.2 (18.1-24.3) | 25.2 (21.0-29.3) | 23.3 (18.2-28.4) |
| Current smoking status | 14.8 (12.3-17.4) | 20.9 (18.2-23.6) | 19.7 (15.9-23.6) | 18.2 (14.2-22.2) | 14.5 (12.0-17.0) | 14.9 (10.7-19.1) | 13.6 (11.0-16.3) | |
| Ever use of oral contraceptives | 3.2 (1.3-5.1) | 32.0 (28.5-35.4) | 63.1 (58.1-68.2) | 70.6 (66.0-75.2) | 77.5 (74.6-80.5) | 77.5 (73.9-81.2) | 81.9 (78.6-85.3) | |
| Ever use of hormone therapy | 22.7 (18.6-26.9) | 31.5 (27.5-35.40) | 45.0 (40.1-49.9) | 47.0 (42.8-51.2) | 37.2 (32.7-41.6) | 33.0 (28.8-37.2) | 26.6 (21.5-31.6) | |
| Hypertension | 78.4 (74.3-82.6) | 73.5 (69.8-77.1) | 63.0 (59.1-67.0) | 66.8 (62.0-71.7) | 67.2 (62.0-72.3) | 64.5 (60.7-68.2) | 65.0 (60.9-69.1) | 61.7 (57.4-66.0) |
| BMI, mean (SD) | 27.0 (5.3) | 26.5 (5.4) | 27.6 (6.1) | 28.9 (6.2) | 29.5 (7.5) | 29.5 (7.2) | 29.9 (7.5) | 30.0 (7.4) |
| General obesityd | 26.0 (22.1-30.0) | 22.7 (20.2-25.3) | 29.9 (26.6-33.3) | 38.6 (34.3-42.9) | 38.1 (34.4-41.8) | 41.6 (37.1-46.1) | 42.4 (36.8-47.9) | 45.0 (39.2-50.8) |
| Waist circumference, mean (SD), cm | 82.2 (12.1) | 91.2 (12.1) | 94.3 (14.1) | 96.3 (15.0) | 97.5 (16.5) | 98.9 (15.7) | 99.9 (15.7) | 100.3 (16.1) |
| Abdominal obesitye | 28.0 (24.3-31.7) | 54.3 (50.9-57.7) | 64.6 (61.0-68.2) | 67.9 (63.9-71.8) | 69.8 (66.6-73.0) | 73.2 (69.3-77.2) | 74.7 (71.0-78.4) | 75.6 (70.3-80.8) |
| Self-reported diabetes | 4.0 (2.6-5.4) | 5.9 (3.9-7.9) | 8.6 (6.6-10.6) | 9.3 (6.8-11.9) | 14.0 (11.5-16.5) | 13.6 (10.4-16.8) | 14.3 (11.7-16.8) | 14.9 (11.5-18.4) |
| Early menopausef | 16.7 (13.9-19.50) | 12.7 (10.2-15.2) | 15.0 (12.1-17.9) | 11.4 (8.0-14.7) | 10.8 (8.5-13.2) | 11.9 (9.3-14.5) | 12.0 (9.2-14.8) | 11.8 (8.6-15.1) |
| Age at menarche, y | ||||||||
| Mean (SD) | 13.5 (1.6) | 13.4 (1.6) | 12.9 (1.6) | 12.8 (1.7) | 12.7 (1.6) | 12.8 (1.6) | 12.8 (1.7) | 12.7 (1.7) |
| Median (IQR) | 12.8 (11.9-13.9) | 12.8 (11.8-13.8) | 12.3 (11.3-13.3) | 12.2 (11.2-13.1) | 12.1 (11.1-12.9) | 12.2 (11.2-13.3) | 12.2 (11.2-13.2) | 12.1 (11.1-13.3) |
| Age at menopause, y | ||||||||
| Mean (SD) | 48.4 (4.0) | 49.1 (4.0) | 49.2 (4.4) | 49.4 (4.2) | 49.9 (4.3) | 49.9 (4.4) | 49.9 (4.4) | 49.9 (4.5) |
| Median (IQR) | 48.5 (44.8-50.8) | 49.2 (46.0-51.3) | 49.3 (45.5-51.8) | 49.2 (46.1-51.4) | 49.4 (46.5-52.5) | 49.6 (46.6-52.4) | 49.6 (46.7-52.5) | 49.6 (46.4-52.5) |
| Reproductive life span, y | ||||||||
| Mean (SD) | 35.0 (4.2) | 35.7 (4.2) | 36.3 (4.8) | 36.6 (4.5) | 37.2 (4.5) | 37.1 (4.5) | 37.2 (4.8) | 37.1 (4.7) |
| Median (IQR) | 34.7 (31.6-37.5) | 35.8 (32.5-38.1) | 36.2 (32.6-39.3) | 36.6 (33.1-38.8) | 36.7 (33.9-39.8) | 36.9 (33.5-39.6) | 37.1 (33.8-39.9) | 37.0 (33.5-39.8) |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); IQR, interquartile range.
Of 9428 women aged 40-74 years at the time of the survey with natural menopause and without missing age at menopause, 1655 were excluded because of menopause due to medical treatment or other reasons (n = 477), age at natural menopause before age 40 years or after age 62 years (n = 672), or race/ethnicity other than Black, White, or Hispanic (n = 506), resulting in an analytic sample of 7773 women. Data are survey-weighted and are reported as % (95% CI) unless otherwise specified. No data are given for information not collected in 1959-1962.
Race/ethnicity was self-reported by all participants in the National Health and Nutrition Examination Survey; for the National Health Examination Survey I (1959-1962), it was determined by interviewer observation and confirmed when possible by birth certificate.
Ratio of family income to the poverty threshold defined by the US Census Bureau appropriate to the family’s composition. The poverty threshold of less than 1.3 corresponds to a family income that is 130% of the poverty level for that survey year (eg, in 2008, a poverty income ratio of 130% was equivalent to approximately $29 000 for a family of 4).
Defined as BMI ≥30.
Defined as waist circumference >88 cm.
Defined as age at natural menopause between 40 and 45 years.
Results
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).
Table 2. Odds Ratios for Factors Associated With Age at Menopause and Reproductive Life Span Among US Women, 1959-2018.
| Factors | Age at menopausea | Reproductive life spanb | ||||||
|---|---|---|---|---|---|---|---|---|
| Bivariable analysis | Multivariable analysisc | Bivariable analysis | Multivariable analysisc | |||||
| Odds ratio (95% CI) | P value | Odds ratio (95% CI) | P value | Odds ratio (95% CI) | P value | Odds ratio (95% CI) | P value | |
| Age | 1.07 (1.06-1.08) | <.001 | 1.07 (1.06-1.08) | <.001 | 1.05 (1.04-1.06) | <.001 | 1.05 (1.04-1.07) | <.001 |
| Race/ethnicityd | ||||||||
| White | 1 [Reference] | <.001 | 1 [Reference] | .006 | 1 [Reference] | <.001 | 1 [Reference] | .04 |
| Black | 0.78 (0.68-0.89) | 0.85 (0.72-1.01) | 0.80 (0.70-0.91) | 0.82 (0.70-0.97) | ||||
| Hispanic | 0.65 (0.57-0.74) | 0.70 (0.55-0.88) | 0.75 (0.67-0.85) | 0.81 (0.65-1.01) | ||||
| Non–US born | 0.84 (0.72-0.99) | .04 | 1.10 (0.86-1.40) | .45 | 0.78 (0.67-0.91) | .002 | 1.00 (0.80-1.25) | .99 |
| Greater than a high-school education | 1.40 (1.24-1.59) | <.001 | 1.36 (1.15-1.60) | <.001 | 1.60 (1.42-1.80) | <.001 | 1.49 (1.29-1.72) | <.001 |
| Poverty | 0.71 (0.63-0.81) | <.001 | 0.83 (0.71-0.97) | .02 | 0.69 (0.61-0.78) | <.001 | 0.82 (0.70-0.95) | .01 |
| Smoking status | ||||||||
| Never | 1 [Reference] | <.001 | 1 [Reference] | <.001 | 1 [Reference] | <.001 | 1 [Reference] | <.001 |
| Former | 0.84 (0.72-0.98) | 0.75 (0.63-0.88) | 0.85 (0.74-0.99) | 0.76 (0.65-0.88) | ||||
| Current | 0.46 (0.39-0.55) | 0.57 (0.47-0.69) | 0.54 (0.46-0.64) | 0.65 (0.54-0.77) | ||||
| Obesity | ||||||||
| General | 1.12 (1.00-1.25) | .06 | 1.00 (0.85-1.18) | .98 | 1.32 (1.17-1.49) | <.001 | 1.19 (1.00-1.42) | .04 |
| Abdominal | 1.28 (1.13-1.45) | <.001 | 1.05 (0.87-1.27) | .61 | 1.45 (1.28-1.65) | <.001 | 1.10 (0.91-1.33) | .32 |
| Age at menarche | 1.04 (1.01-1.07) | .02 | 1.05 (1.01-1.10) | .007 | ||||
| Ever use of oral contraceptives | 1.10 (0.98-1.25) | .12 | 1.26 (1.08-1.48) | .005 | 1.25 (1.11-1.41) | <.001 | 1.34 (1.15-1.56) | <.001 |
| Ever use of hormone therapy | 1.09 (0.95 1.25) | .22 | 0.87 (0.75-1.00) | .05 | 1.05 (0.91-1.20) | .49 | 0.84 (0.73-0.97) | .02 |
| Hypertension | 1.21 (1.04-1.40) | .01 | 1.10 (0.94-1.29) | .25 | 1.19 (1.03-1.37) | <.001 | 1.11 (0.95-1.29) | .20 |
| Self-reported diabetes | 1.12 (0.94-1.34) | .20 | 1.08 (0.86-1.35) | .50 | 1.14 (0.96-1.34) | .13 | 1.02 (0.83-1.26) | .83 |
The bivariable and multivariable cumulative logit models were fitted to predict the odds of higher age at menopause, categorized as <45, 45-49, 50-54, and ≥55 years.
The bivariable and multivariable cumulative logit models were fitted to predict the odds of longer reproductive life span, categorized as <33, 33-36, 37-39, and ≥40 years.
Multivariable model adjusted for all factors listed in the table.
Interaction tests for differences in trends of age at menopause and reproductive life span by race/ethnicity were not statistically significant (P = .70 and P = .35, respectively).
Discussion
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.
Section Editor: Jody W. Zylke, MD, Deputy Editor.
References
- 1.Gold EB. The timing of the age at which natural menopause occurs. Obstet Gynecol Clin North Am. 2011;38(3):425-440. doi: 10.1016/j.ogc.2011.05.002 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Schoenaker DA, Jackson CA, Rowlands JV, Mishra GD. Socioeconomic position, lifestyle factors and age at natural menopause. Int J Epidemiol. 2014;43(5):1542-1562. doi: 10.1093/ije/dyu094 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.National Center for Health Statistics, Centers for Disease Control and Prevention . NHANES questionnaires, datasets, and related documentation. Accessed October 28, 2020. https://wwwn.cdc.gov/nchs/nhanes/default.aspx
- 4.Costanian C, McCague H, Tamim H. Age at natural menopause and its associated factors in Canada. Menopause. 2018;25(3):265-272. doi: 10.1097/GME.0000000000000990 [DOI] [PubMed] [Google Scholar]
- 5.Nichols HB, Trentham-Dietz A, Hampton JM, et al. From menarche to menopause: trends among US women born from 1912 to 1969. Am J Epidemiol. 2006;164(10):1003-1011. doi: 10.1093/aje/kwj282 [DOI] [PubMed] [Google Scholar]
- 6.Bjelland EK, Hofvind S, Byberg L, Eskild A. The relation of age at menarche with age at natural menopause. Hum Reprod. 2018;33(6):1149-1157. doi: 10.1093/humrep/dey078 [DOI] [PMC free article] [PubMed] [Google Scholar]