17-beta-estradiol in relation to age at menarche and adult obesity in premenopausal women.

Abstract

BACKGROUND: We hypothesize that premenopausal endogenous estradiol may be associated with age at menarche and adult overweight and obesity, potentially contributing to breast cancer risk. METHODS: We assessed age at menarche by questionnaire among 204 healthy Norwegian women, aged 25-35 years. Measures of body composition included body mass index (BMI, kg/m(2)), waist circumference (WC, cm), waist-to-hip ratio (WHR) and fat percentage dual energy X-ray absorptiometry, (DEXA). Daily salivary 17-beta-estradiol (E(2)) concentrations were collected throughout one entire menstrual cycle and assessed by radioimmunoassay (RIA). Linear regression analyses and linear mixed models for repeated measures were used and potential confounding factors and effect modifiers were tested. RESULTS: Among women with an early age at menarche (