Measures of menopausal status in relation to demographic, reproductive, and behavioral characteristics in a population-based study of women aged 35-49 years

The purpose of this cross-sectional analysis of women aged 35-49 years from the Third National Health and Nutrition Examination Survey, conducted betw een 1988 and 1994, was to assess associations with menopausal status based either on menstrual cycle patterns or on elevated (> 20 IU/liter) follicle- stimulating hormone. Menstrual cycle-based menopausal status was defined fo r women who had not had surgical menopause by months since the last period (<2, 2-12, and > 12 months for pre-, peri-, and postmenopause, respectively ). Logistic regression was adjusted for age, smoking, and unilateral oophor ectomy, Higher body mass index (greater than or equal to 30 kg/m(2) compare d with < 25.0 kg/m(2)) was associated with a lower likelihood of elevated f ollicle-stimulating hormone (odds ratio (OR) = 0.6, 95% confidence interval (CI): 0.4, 0.9) but this association was not seen with the menstrual measu re of menopause. Exercise (three or more times per week) was associated wit h a lower likelihood of being postmenopausal on the basis of menstrual (OR = 0.3, 95% CI: 0.2, 0.7) and hormonal (OR = 0.6, 95% CI, 0.4, 1.0) measures . Alcohol use also tended to be associated with postmenopausal status by ei ther measure, but not significantly so. There was little evidence of associ ations with ethnicity, education, age at menarche, number of livebirths, an d oral contraceptive use. Menstrual-based definitions of menopause can be m isclassified for women with menstrual irregularity. This might explain why obese women were classified menstrually as menopausal while remaining hormo nally premenopausal.