OBJECTIVE - Modifiable factors predicting the onset of menopause, a transition with important implications for women's health, have not been fully characterized. We evaluated the impact of dietary, lifestyle and reproductive factors on age at natural menopause and reproductive span in Chinese women.
DESIGN - Study participants were Chinese women aged 40 to 70 who experienced natural menopause and participated in a population-based, prospective study, the Shanghai Women's Health Study (N = 33,054). Dietary intake at the baseline survey was assessed by food-frequency questionnaire. Regression (beta) coefficients, calculated by multivariable linear regression, were used to estimate the effects of dietary, lifestyle, and reproductive patterns on age at menopause and the number of reproductive years, adjusting for potential confounding factors.
RESULTS - Early menarche, younger age at first live birth, older age at last live birth, longer duration of breast-feeding, and higher parity were associated with longer reproductive years (Ptrend < 0.01 for all). Higher body mass index at age 20, mid-life weight gain, and leisure-time physical activity during adolescence and adulthood predicted later menopause and longer reproductive span (Ptrend < 0.01 for all). Total intake of calories, fruits, and protein was positively associated with later menopause (Ptrend < 0.05 for all) and longer reproductive span (Ptrend < 0.05), except for carbohydrates (Ptre(nd) = 0.06), and long-term tea consumption predicted longer reproductive span (Ptrend = 0.03). Vegetable, fat, soy, and fiber intakes did not significantly affect reproductive span or age at menopause. Smoking was inversely associated with both early age at menopause and shorter reproductive span (Ptrend < 0.01).
CONCLUSIONS - In addition to reproductive factors, intake of fruits and protein, smoking, tea consumption, lifetime patterns of physical activity, and weight gain influenced the onset of menopause and/or reproductive span in Chinese women.