Oral Contraceptive Use and Reproductive History in Relation to Metabolic Syndrome Among Women from KNHANES 2010-2023

Background/Objectives: This study examined how reproductive factors-such as oral contraceptive (OC) use, age at menarche, number of pregnancies, and age at first delivery-are related to the risk of metabolic syndrome (MetS) in Korean women aged 30-69, based on their menopausal status. Methods: Data from the Korea National Health and Nutrition Examination Survey 2010-2023 were analyzed, including 31,178 women with complete data. Survey-weighted logistic regression and restricted cubic spline analyses were conducted, adjusting for sociodemographic, lifestyle, and reproductive covariates. Results: OC use was associated with higher MetS risk in both pre-menopausal (adjusted OR 1.40, 95% CI 1.13-1.72) and post-menopausal women (adjusted OR 1.16, 95% CI 1.03-1.29). This association was observed primarily in relation to elevated blood pressure in both groups and high triglycerides in post-menopausal women. Other reproductive factors, including age at menarche, number of pregnancies, and age at first delivery, showed no significant associations with MetS risk. Conclusions: OC use was associated with higher MetS risk in this cross-sectional study of Korean women. These observational findings suggest a potential relationship that warrants further investigation through longitudinal studies to establish temporal relationships and explore underlying mechanisms.