In one of the world’s lowest-fertility countries, reproductive risk factors for ovarian cancer are shifting across generations. A nationwide cohort study of 2,285,774 Korean women followed for more than a decade found the classic protective factors of increased parity and lower lifetime hormonal exposure (read: later menarche and earlier menopause) held true only for older, higher-fertility generations born prior to the 1960s. On the other hand, breastfeeding and oral contraceptive use showed clearer protective associations for younger, lower-fertility generations. | Kim, JAMA Netw Open 2026
