Adiposity and reporting of vasomotor symptoms among midlife women: the study of women's health across the nation.

It has long been hypothesized that increased adiposity would be associated with decreased vasomotor symptoms during menopause because of conversion of androgens to estrogens in body fat. However, recent thermoregulatory models have postulated that increased adipose tissue would be associated with a greater likelihood of vasomotor symptoms. The authors evaluated these hypotheses in the Study of Women's Health Across the Nation, a multiethnic, community-based observational study of US women transitioning through menopause. The sample included 1,776 women aged 47-59 years with an intact uterus and at least one ovary who completed bioelectrical impedance analysis for assessment of body composition at the sixth annual study visit (2002-2004). Assessments also included reported vasomotor symptoms (hot flashes, night sweats) and serum levels of follicle-stimulating hormone, estradiol, and sex hormone-binding globulin-adjusted estradiol (free estradiol index). Results indicated that a higher percentage of body fat was associated with increased odds of reporting vasomotor symptoms (per standard deviation increase in percent body fat, odds ratio = 1.27, 95% confidence interval: 1.14, 1.42) in age- and site-adjusted models. Associations persisted in fully adjusted models and were not reduced when models included reproductive hormones. These findings support a thermoregulatory model of vasomotor symptoms.