Objective
We sought to examine regional and black-white differences in mean age at self-reported menopause among community-dwelling women in the United States.
Study Design
This was a cross-sectional survey conducted in the context of the REasons for Geographic And Racial Differences in Stroke and Myocardial Infarction study.
Results
We studied 22,484 menopausal women. After controlling for covariates, Southern women reported menopause 10.8 months earlier than Northeastern women, 8.4 months earlier than Midwestern women, and 6.0 months earlier than Western women ( P < .05 for all). No difference was observed in menopausal age between black and white women after controlling for covariates ( P = .69).
Conclusion
Women in the South report earlier menopause than those in other regions, but the cause remains unclear. Our study’s large sample size and adjustment for multiple confounders lends weight to our finding of no racial difference in age at menopause. More study is needed of the implications of these findings with regard to vascular health.
Menopause occurs most often between the ages of 50-52 years, with 95% of women having final menstrual period between ages 44-56 years. Early menopause has been associated with higher all-cause mortality and an increased incidence in cardiovascular disease (CVD) risk factors, both significant public health concerns. Several factors have been associated with age at menopause. Women who smoke stop menstruating 1-2 years earlier than comparable nonsmokers. Women who use oral contraceptives, who have higher socioeconomic status, and higher parity have later menopause. Mother’s age at menopause is also an important predictor of daughter’s age at menopause. Data regarding racial differences in age at menopause have been mixed with several small studies reporting that menopause occurs approximately 6 months earlier in black women when compared to age-matched white women, while other larger studies have reported no racial difference.
Though CVD has been associated with an earlier age at menopause, the reasons for this association are not known. The Southeastern United States is a region described to have higher stroke and coronary heart disease mortality than elsewhere in the country. Whether women living in these higher CVD mortality regions also have lower age at menopause has not been reported. This type of analysis is complicated by the clustering of blacks in the Southeast.
In this article, we examined the relationship of age at menopause with race and geographic region in the United States. We hypothesized that menopause occurs earlier in the South compared to other regions in the United States, consistent with the high CVD mortality there. Furthermore, we sought to determine if any observed regional differences could be explained by race or other factors thought to affect age at menopause.
Materials and Methods
REasons for Geographic And Racial Differences in Stroke (REGARDS) is a national, community-based study of >43,000 black and white men and women aged ≥45 years, designed to examine underlying mechanisms leading to regional and racial differences in stroke. An ancillary study examines differences in acute coronary heart disease outcomes. To construct the cohort, individuals were consented and interviewed by computer-assisted telephone interview (CATI), and if they also agreed to an in-home examination, were entered into the cohort. This report includes the 22,484 women who completed the CATI survey regardless of having a home visit and reported having already undergone menopause at the time of the interview.
REGARDS recruitment took place from 2003 through 2007, and methods are detailed elsewhere. Briefly, community-dwelling women interviewed for REGARDS resided in all regions in the continental United States, both rural and urban areas, and 48.9% (n = 10,998) were white and 51.1% (n = 11,486) were black. Race was self-reported, and our cohort includes only 2 racial groups: blacks and whites. The use of “racial differences” in this article refers only to these 2 racial groups.
The Southern region had a larger number of participants than other regions due to statistical power required to test regional differences in stroke incidence and mortality in the larger study. The CATI survey included questions on medical history, including reproductive history. To assess for menopausal status, participants were asked, “Have you gone through the change of life?” and “How old were you at the time of your last natural menstrual period?” To identify those with surgical menopause, participants were asked, “Have you ever had a hysterectomy, that is, surgery to remove your uterus or womb?” and “Have you ever had an ovary removed?” If they answered “yes” to the latter, participants were asked, “How many ovaries were removed?” Women who underwent an iatrogenic early menopause were identified if they answered positively to the following question: “Have you had any condition or treatment that caused your menstrual periods to permanently stop, other than the surgeries we just discussed or natural menopause?” Other surgical procedures involving the fallopian tubes and uterus, such as tubal ligation, endometrial ablation, and myomectomy were not included in the reproductive history portion of the interview. Women with a history of hormone use, both for contraceptive and replacement purposes, were included in the analysis.
We divided the study sample into “naturally” and “surgically” menopausal women. Naturally menopausal women were defined as those reporting that their last menstrual period was ≥12 months prior to their CATI. Women who stopped menstruating 12 months prior to having hysterectomy and/or oophorectomy were also considered naturally menopausal. Surgically menopausal women included those who reported a history of hysterectomy or removal of both ovaries. The relatively small number of women reporting unilateral oophorectomy without hysterectomy (3%) was included in the “natural” menopause group in the analysis since loss of 1 ovary was not expected to confer a large difference in age at menopause. Participants were excluded if they reported still having regular menstrual periods at the time of initial CATI or reported their last period within 12 months of the initial CATI. Participants who reported undergoing menopause either naturally or surgically, but did not identify a specific age, were included in separate analyses.
Univariate analyses of variance were used to test associations between self-reported age at menopause and race (black and white) and region among women in the natural and surgical menopause groups. The self-reported age at menopause was defined as the age in years reported by study participants at which their last menstrual period occurred. For the surgical menopause analysis, the age at menopause was defined as the self-reported age in years when the participants underwent the earliest surgical procedure that met the surgical criteria stated previously. Regions were defined by 4 geographic regions utilized by the US Census Bureau: South, Northeast, Midwest, and West ( Figure 1 ). A subanalysis of the South region was performed to evaluate differences in age at menopause among areas of increased stroke mortality, the Stroke Belt and Stroke Buckle. The Stroke Buckle includes the coastal plain region of North and South Carolina and Georgia, and the Stroke Belt includes remainder of North and South Carolina and Georgia, and the states of Tennessee, Alabama, Mississippi, Louisiana, and Arkansas.
We used multiple linear regression to examine racial and regional differences in age at menopause, and pairwise comparisons were performed in both racial and regional analyses to adjust for variables known to be associated with menopausal age: chronological age, parity, smoking history, and socioeconomic status. All variables were examined simultaneously. Annual income and education were utilized as surrogates for socioeconomic status. History of CVD was also included as a covariate given an association with earlier menopause as previously discussed. The CVD variable included self-reported history of myocardial infarction, stroke, transient ischemic event, carotid endarterectomy, coronary intervention, repair of aortic aneurysm, and/or peripheral arterial intervention. Physical activity was entered as a covariate in the analysis because a European study recently illustrated an association between earlier menopause and both decreased physical activity and higher body mass index (BMI). Extent of physical activity was assessed by the CATI with the following question: “How many times per week do you engage in intense physical activity, enough to work up a sweat.” Measured BMI was entered as a covariate in a separate analysis for those participants who underwent an in-home visit (7167 women or 68.5%) to elucidate if this might explain differences observed in age at menopause. Less than 0.5% of all data points were missing after interviewing REGARDS respondents, with the exception of annual income and physical activity, where 16.9% and 1.6% of respondents, respectively, did not provide an answer. For income those with missing data were included in the analysis and coded as missing.
Results
Sample characteristics
Women in the natural (n = 10,440) and surgical (n = 9944) menopause groups differed somewhat with respect to age, parity, and smoking history ( Table 1 ). A greater proportion of women in the surgical menopause group were black and resided in the South. In addition, women in the surgical menopause group tended to have lower education and lower annual income. Women with surgical menopause had a proportionately greater prevalence of self-reported CVD.
| Variable | Natural (n = 10,440), n (%) | Surgical (n = 9944), n (%) | P value compared to natural | Not reported age at natural (n = 1361), n (%) | P value compared to natural | Not reported age at surgical (n = 739), n (%) | P value compared to surgical |
|---|---|---|---|---|---|---|---|
| Region | |||||||
| South | 6750 (64.7) | 7307 (73.5) | < .0001 | 899 (66.1) | .35 | 555 (75.2) | .48 |
| Northeast | 945 (9.1) | 517 (5.2) | 106 (7.8) | 37 (5.0) | |||
| Midwest | 1555 (14.9) | 1279 (12.9) | 193 (14.2) | 96 (13.0) | |||
| West | 1185 (11.4) | 833 (8.4) | 162 (11.9) | 50 (6.8) | |||
| Race | |||||||
| White | 5479 (52.5) | 4738 (47.7) | < .0001 | 781 (57.4) | < .0001 | 201 (27.2) | < .0001 |
| Black | 4961 (47.5) | 5206 (52.4) | 580 (42.6) | 538 (72.8) | |||
| Age, y | |||||||
| <55 | 987 (9.5) | 1144 (11.5) | < .0001 | 55 (4.0) | < .0001 | 20 (2.7) | < .0001 |
| 55-64 | 4334 (41.5) | 3959 (39.8) | 394 (29.0) | 164 (22.2) | |||
| 65-74 | 3184 (30.5) | 3230 (32.5) | 466 (34.2) | 287 (38.8) | |||
| ≥75 | 1935 (18.5) | 1611 (16.2) | 446 (32.8) | 268 (36.3) | |||
| Parity | |||||||
| 0 | 1261 (12.1) | 1032 (10.4) | .0004 | 171 (12.7) | .28 | 93 (12.7) | .09 |
| 1 | 1441 (13.8) | 1441 (14.5) | 206 (15.2) | 94 (12.8) | |||
| ≥2 | 7710 (74.1) | 7456 (75.1) | 975 (72.1) | 546 (74.5) | |||
| Annual income | |||||||
| <$20,000 | 2538 (24.3) | 2523 (25.4) | .003 | 342 (25.1) | < .0001 | 251 (34.0) | < .0001 |
| $20,000-34,999 | 2594 (24.9) | 2596 (26.1) | 273 (20.1) | 155 (21.0) | |||
| $35,000-74,999 | 2628 (25.2) | 2415 (24.3) | 196 (14.4) | 91 (12.3) | |||
| ≥$75,000 | 1076 (10.3) | 896 (9.0) | 95 (7.0) | 11 (1.5) | |||
| Refused | 1604 (15.4) | 1514 (15.2) | 455 (33.4) | 231 (31.3) | |||
| Education level | |||||||
| <HS | 1503 (14.4) | 1724 (17.4) | < .0001 | 320 (23.6) | < .0001 | 217 (29.4) | < .0001 |
| Graduated HS | 2881 (27.6) | 3020 (30.4) | 379 (27.9) | 229 (31.1) | |||
| Some college a | 2793 (26.8) | 2802 (28.2) | 314 (23.1) | 145 (19.7) | |||
| Graduated college | 3248 (31.2) | 2387 (24.0) | 346 (25.5) | 146 (19.8) | |||
| Self-reported history of CVD b | |||||||
| No | 8607 (82.4) | 7844 (78.9) | < .0001 | 1083 (79.6) | .009 | 541 (73.2) | .0003 |
| Yes | 1833 (17.6) | 2100 (21.1) | 278 (20.4) | 198 (26.8) | |||
| Physical activity/wk | |||||||
| None | 4058 (39.5) | 4084 (41.6) | .0003 | 644 (48.9) | < .0001 | 368 (51.3) | < .0001 |
| 1-3 | 3570 (34.7) | 3415 (34.8) | 386 (29.3) | 220 (30.7) | |||
| ≥4 | 2658 (25.8) | 2312 (23.6) | 288 (21.9) | 129 (18.0) | |||
| Smoking | |||||||
| Never | 5407 (52.0) | 5302 (53.5) | .09 | 761 (56.5) | .002 | 423 (58.1) | .01 |
| Current | 1622 (15.6) | 1476 (14.9) | 170 (12.6) | 83 (11.4) | |||
| Past | 3365 (32.4) | 3128 (31.6) | 415 (30.8) | 222 (30.5) |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
