Objectives: Exposures which might influence age at natural menopause have been extensively studied but, with the exception of cigarette smoking, results have been inconsistent. We sought to determine: (i) whether alcohol and caffeine intake are associated with age at menopause; (ii) whether the association of cigarette smoking with age at menopause is confined to current smokers.
Methods: Analyses drew on longitudinal data from 494 women, aged 44-60 in 1993, of whom 159 experienced menopause before intake or during follow-up. We used parametric logistic survival analysis to estimate shifts in median age at menopause for women who drink alcohol or caffeine or who smoke cigarettes.
Results: The estimated median age at menopause was 2.2 (95% confidence interval (CI) 0.5, 3.9) years later for women who drank alcohol 5-7 days/week (13% of the sample) than for women who did not drink alcohol (54%). For women who drank at least 1 day/week, the estimated shift was 1.3 (95% CI 0.2, 2.3) years. Caffeine intake in approximate quartiles of mg/day-0-100, >100-200, >200-400, 400+-was not related to age at menopause. Current smokers of 14+cigarettes/day (6%) experienced menopause 2.8 (95% CI -4.8, -0.8) years earlier than women who never smoked (51%). Current smokers of 1-13 cigarettes/day (5%) and former smokers (38%) experienced menopause at about the same age as women who never smoked.
Conclusions: The results are compatible with a pro-estrogenic effect of moderate alcohol intake and an anti-estrogenic effect of current cigarette smoking of 14+cigarettes/day.