Smoking and age at natural menopause in a cross-sectional study of Turkish women

Background: Smoking is known to advance the age at natural menopause (ANM). Whether passive smoke exposure may alter ANM is not known
Methods: Between 09.2006-02.2008, a convenience sample of 1106 women, born between 1946-1962, who had no history of major chronic disease and conditions that may obscure the determination of ANM were recruited for a cross-sectional study. Cox proportional hazard modeling is used to determine predictors of ANM. Antropometric factors, socioeconomic factors, timing of maternal menopause, premenopausal active and passive smoke exposure, alcohol use and reproductive factors were evaluated as predictors.
Results: Postmenopausal women comprised 45.9 % (n= 508). Median ANM is 52. Ninety-seven (%8.8) women reported premenopausal active smoking. Only 127 women (11.5 %) had never been premenopausally exposed to passive smoke. In univariate analysis greater height, older age at maternal menopause, later year of birth, better economic status, higher monthly income and higher education were associated with later ANM; whereas ever having smoked before menopause, premenopausal packyears of smoking, ever having used alcohol before menopause and premenopausal cumulative use of alcohol were associated with earlier menopause. In multivariate analyses, ever having smoked before menopause was the strongest predictor of ANM but pack-years of smoking was not significant. Though not significant in univariate analyses greater cumulative exposure to passive smoke (years) and later age at menarche was found to be associated with later menopause in multivariate analyses. In multivariate analyses all other mentioned predictors of ANM remained significant except for ever and cumulative use of alcohol and educational status.
Conclusions: Having smoked before menopause is strongly associated with an earlier ANM while premenopausal cumulative exposure to passive smoke may be associated with later menopause. To our knowledge this study is the first to suggest that active and passive smoke exposures may have opposite effects on ANM. Supported by TUBITAK-106S079(SBAG-3357)