Objective: We analyzed the relation between factors related to endogenous female hormones and the risk of acute myocardial infarction (AMI).
Study design: We used a combined dataset from three Italian case-control studies, including 609 women with non-fatal AMI and 1106 controls hospitalized for acute conditions.
Results: The odds ratios (OR) of AMI were 1.36 (95% confidence intervals, CI 0.95-1.96) in women with an irregular menstrual pattern compared to a regular one, and 1.45 (95% CI 1.07-1.97) in parae compared to nulliparae, without linear trend in risk with number of children. No relation was found with menopausal status, age at menarche and menopause, abortion, and age at first and last birth. Compared to women without abortions the OR was 0.84 (95% CI 0.60-1.18) for >1 abortion; compared to women without spontaneous or induced abortion, the ORs were 0.92 (95% CI 0.62-1.38) for >1 spontaneous and 0.63 (95% CI 0.36-1.08) for >1 induced abortion. The association of parity and irregular menstrual cycles was stronger in pre-/peri-menopausal women and in current smokers. Compared to nonsmokers with regular menstrual cycle, the OR was 5.98 (95% CI 3.38-10.56) for smokers with irregular one, and compared to nonsmokers nulliparae the OR for smokers parae was 4.77 (95% CI 3.12-7.29).
Conclusions: Irregular menstrual cycles and parity were related to increased AMI risk, mainly among pre-/peri-menopausal women and among smokers.