Menstrual and Reproductive Factors for Gastric Cancer in Postmenopausal Women: The 2007–2020 Korea National Health and Nutrition Examination Survey

Globally, the incidence of gastric cancer is lower in women than in men. It is thought that menstrual and reproductive factors may be related to their lower incidence of gastric cancer. This cross-sectional study examined menstrual, reproductive, and other factors in 20,784 postmenopausal women from the 2007–2020 Korea National Health and Nutrition Examination Survey (KNHANES). A univariate logistic regression analysis was performed, and then a multivariate logistic regression analysis for significant factors in the univariate analysis was conducted. In the multivariate logistic regression analysis, the age at menarche (odds ratio [OR] 1.08, 95% confidence interval [CI] 1.00−1.06, p = 0.035) and myocardial infarction (OR 2.43, 95% CI 1.05−5.62, p = 0.026) showed a significant association with increased incidence of gastric cancer. The age at menopause (OR 0.97, 95% CI 0.95−1.00, p = 0.03), the age at the first childbirth (OR 0.93, CI 0.89−0.97, p = 0.007), and the experience of alcohol consumption (OR 0.68, 95% CI 0.5–0.91, p = 0.003) showed a significant association with a decreased incidence of gastric cancer. Late menarche, early menopause, early aged first childbirth, and myocardial infarction are estimated to be risk factors for gastric cancer in postmenopausal Korean women.