Helping midlife women predict the onset of the final menses: SWAN, the Study of Women's Health Across the Nation.

OBJECTIVE

Women approaching menopause often ask their doctors, "When are my periods going to end?" The objective of this study was to predict time to the final menstrual period (FMP).

DESIGN

This multiethnic, observational cohort study, the Study of Women's Health Across the Nation, has been ongoing since 1996. Data collected from seven annual study visits were used. The community-based cohort from seven national sites included 3,302 white, African American, Hispanic, Chinese, and Japanese women aged 42 to 52 years at baseline with a uterus and at least one ovary, who were not pregnant or taking reproductive hormones, and had at least one menstrual period within the past 3 months at baseline. The time to the FMP was defined retrospectively after 12 months of amenorrhea. Uni- and multivariable Cox proportional hazard models, hazard ratios (HRs), and 95% CIs were computed for variables of interest.

RESULTS

A total of 2,662 women, of whom 706 had an observed FMP, were included. Age, menstrual cycles that had become farther apart (HR = 2.56, 95% CI = 1.94-3.39) or more variable (HR = 1.79, 95% CI = 1.45-2.21), and current smoking (HR = 1.68, 95% CI = 1.35-2.08) were all associated with shorter time to the FMP. Higher (log) follicle-stimulating hormone (HR = 2.32, 95% CI = 2.02-2.67) was related to a shorter time to the FMP, but the highest estradiol category (>or=100 pg/mL [367 pmol/L]) was associated with an earlier onset of the FMP (HR = 2.16, 95% CI = 1.63-2.89). The number of vasomotor symptoms was related to an earlier FMP, whereas higher physical activity and educational levels were associated with a later FMP.

CONCLUSIONS

Age, menstrual cycle recall, smoking status, and hormone measurements can be used to estimate when the FMP will occur, allowing for more precise estimates for older midlife women: in the most extreme cases, ie, age 54, high estradiol level, current smoking, and high follicle-stimulating hormone level, the FMP can be estimated to within 1 year.