Change in Body Mass Index, Weight, and Hot Flashes: A Longitudinal Analysis from the Midlife Women's Health Study

Background: The goals of this study were to examine the associations between body mass index (BMI), as well as BMI change and weight change, with midlife hot flashes. Methods: Data were analyzed from an ongoing 5-year cohort study of 631 midlife women (ages 45-54 years) recruited from Baltimore, Maryland, and its surrounding counties. Height and weight were measured at clinic visits conducted annually. Questionnaires administered at each clinic visit collected detailed data on hot flashes, including the severity and frequency, and other covariates. Data were analyzed using logistic regression and generalized estimated equation models, adjusting for potential confounders. Results: Among women enrolled in the study, 45.2% reported hot flashes and 32.0% were categorized as being obese (BMI 30kg/m(2)) at baseline. At baseline, BMI was not significantly associated with ever experiencing hot flashes (BMI 30 versus <25kg/m(2): odds ratio [OR] 0.92; 95% confidence interval [CI]: 0.58, 1.15) or any of the other hot flashes outcomes (recent, frequent, or severe). In addition, no statistically significant associations between BMI, BMI change, or weight change, and the hot flash outcomes were observed in the longitudinal models (for example, any hot flashes: BMI 30 versus <25kg/m(2): OR 0.81; 95% CI: 0.56, 1.17). Conclusion: BMI, BMI change, and weight change during midlife were not related to hot flashes in this study. The data suggest that other factors, such as smoking habits, are more important in determining hot flashes risk during midlife.