Body mass index in mid-life women: relative influence of menopause, hormone use, and ethnicity

OBJECTIVE: To assess the relative influence of menopausal status and hormon e use on body mass index (BMI) among a multiethnic sample of mid-life women . DESIGN: Cross-sectional telephone survey conducted at seven sites where eac h site targeted an ethnic minority group and Caucasians as part of Study of Women's Health Across the Nation (SWAN). SUBJECTS: A total of 7181 Caucasians, 3949 African-Americans, 1660 Hispanic s, 562 Chinese Americans, and 803 Japanese Americans between ages of 40 and 55 y residing in or near Boston, Chicago, Detroit, Los Angeles, Newark, Nj , Oakland, CA, and Pittsburgh, PA. MEASUREMENTS: Self-reported BMI based on weight in kg divided by height in m(2) menopausal status, physical inactivity, postmenopausal hormone use, et hnicity, and age in years. RESULTS: Compared to premenopausal women (covariate adjusted M = 27.3), wom en reporting a surgical menopause (M = 28.2) or being in the perimenopausal transition (M = 27.7 for early and 27.9 for late perimenopause) had higher BMI. Women reporting a natural menopause (M = 27.4) did not have a higher BMI than premenopausal women, after adjusting for chronological age and oth er covariates. Hormone use was associated with lower BMI (M = 26.5 vs 27.3) . A comparison of effect sizes showed that menopausal status (F = 13.1), fo llowed by chronological age (F = 24.0), were the least powerful predictors of BMI, whereas the more powerful predictors were physical activity level ( F = 1377.1) and ethnicity (F = 400.5). CONCLUSIONS: The menopausal transition affects body mass index in mid-life, but the effect is small relative to other influences. Interventions to inc rease physical activity are highly recommended to prevent increases in adip osity common in mid-life.