Objective: The purpose of this study was to evaluate the relationship between certain reproductive and lifestyle factors and the occurrence of early natural menopause.
Material and methods: A case/control study was conducted on a basal population of 2510 women participating in the "Mexican Institute of Social Security health workers cohort study". Cases were defined as those women for whom natural menopause presented by age 47. Information was obtained through a self-administered questionnaire.
Results: The risk of early menopause is associated with short menstrual cycles [<26 days, OR = 3.79 (IC 95% 1.37-10.52)], a short period of oral contraceptives use [<1 year, OR = 2.63 (IC 95% 1.10-6.29)], a lower number of pregnancies [<2, OR = 1.63 (IC 95% 1.03-2.57)], low body mass index [< or =27 kg/m2, OR = 1.64 (IC 95% 1.10-2.43)], low schooling level [<6 years, OR = 3.02 (IC 95% 1.26-7.23)], smoking history [>15 cigarettes/day, OR = 2.7 (IC 95% 1.00-7.30)], and birth cohorts [> or =950, OR = 4.09 (IC 95% 2.62-6.39)].
Conclusions: The findings of this study suggest that both reproductive and lifestyle factors are significant elements in the occurrence of early menopause in Mexican women.