Uterine leiomyomata are a major source of morbidity in black women. We prospectively investigated the risk of self-reported uterine leiomyomata in relation to body mass index (BMI), weight change, height, waist and hip circumferences, and waist-to-hip ratio in a large cohort of U.S black women.
Data were derived from the Black Women’s Health Study, a U.S. prospective cohort study of black women who complete biannual mailed health questionnaires. From 1997 through 2001, we followed 21,506 premenopausal women with intact uteri and no prior diagnosis of uterine leiomyomata. Cox regression models were used to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CIs).
After 70,345 person-years of follow up, 2146 new cases of uterine leiomyomata confirmed by ultrasound (n = 1885) or hysterectomy (n = 261) were self-reported. Compared with the thinnest women (BMI <20.0 kg/m2), the multivariate IRRs for women with BMIs of 20.0–22.4, 22.5–24.9, 25.0–27.4, 27.5–29.9, 30.0–32.4, and 32.5= kg/m2 were 1.34 (95% CI = 1.02–1.75), 1.39 (1.07–1.81), 1.45 (1.12–1.89), 1.47 (1.11–1.93), 1.36 (1.02–1.80), and 1.21 (0.93–1.58), respectively. IRRs were larger among parous women. Weight gain since age 18 was positively associated with risk, but only among parous women. No other anthropometric measures were associated with risk.
BMI and weight gain exhibited a complex relation with risk of uterine leiomyomata in the Black Women’s Health Study. The BMI association was inverse J-shaped and findings were stronger in parous women. Weight gain was positively associated with risk among parous women only.