Because of the high prevalence of hormone use and reproductive surgeries in Western women natural menopause is a less frequent condition. Our aim was to examine the influences of hormonal and other factors on timing of cessation of menses. We analysed population controls of a German case-control study on breast cancer risks. The sample comprised N=829 women without hysterectomy or bilateral oophorectomy. We estimated the risk for the occurrence of last menses by Cox proportional hazard modelling. For calculating hazard rate ratios (HRR) and 95% confidence intervals (CI) women with menstrual cycles up to one year before interview were censored at that age. Median age at cessation of menses was 50 years (inter-quartile range 47–53 years). A significant later cessation of menses resulted from oral contraceptive use (HRR 0.74, 95% CI 0.59–0.93 for up to 10 years), and hormone therapy use until last menses (HRR 0.57, 95% CI 0.47–0.70). Also, thyroidal medications were associated with a delayed cessation of menses (HRR 0.64, 95% CI 0.42–0.96 for more than 10 years of use). Smoking until at least two years before last menses and allergies revealed an earlier cessation of bleedings (HRR 1.50, 95% CI 1.22–1.83 and HRR 1.28, 95% CI 1.07–1.53 respectively). Natural menopause is difficult to determine. Factors affecting the ovaries or the endocrine system can modulate timing of menopause. Endocrine biomarkers should be additionally taken into account when defining menopausal status.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
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