Women with multiple pregnancies face higher fracture risk after menopause, Seoul St. Mary's Hospital study finds

Seoul St. Mary's Hospital of the Catholic University of Korea announced Wednesday that resident physician Seong Gyeong-heon of the internal medicine department won an award at an international academic conference for research showing that women who have given birth multiple times need to proactively monitor their bone health after menopause.

Seong, a second-year resident working under endocrinologist Prof. Ha Jeong-hun, received the Best Oral Presentation Award at the 2026 Seoul Symposium on Bone Health, hosted by the Korean Society for Bone and Mineral Research. The research drew attention for its precise analysis of the link between childbearing history and postmenopausal skeletal health using national big data.

The study, titled "Parity, Cumulative Hormonal Exposure, and Skeletal Health in Postmenopausal Women," analyzed data from 1,420 postmenopausal women drawn from the 2024 Korea National Health and Nutrition Examination Survey published by the Korea Disease Control and Prevention Agency (KDCA), evaluating factors affecting skeletal health.

By tracking the pregnancy and childbirth histories of postmenopausal women, the research team found that women who had been pregnant three or more times faced roughly a 36 percent higher risk of postmenopausal fractures compared with women who had never been pregnant. Precision statistical analyses confirmed the elevated risk at a statistically reliable level.

The hypothesis that multiple pregnancies can negatively affect women's skeletal systems has consistently been raised in prior research. However, differences in study populations and designs made it difficult to draw clear clinical conclusions. This study is considered significant because it used the latest national-scale big data to establish a statistically meaningful link between multiple childbirths and postmenopausal fracture risk.

The "estrogen gap" that occurs during pregnancy is identified as a key pathophysiological mechanism behind the increased fracture risk. Because menstruation stops during pregnancy and breastfeeding, women accumulate less lifetime exposure to estrogen — the hormone that suppresses bone resorption and maintains bone density.

Experts stress that adequate intake of calcium and vitamin D is necessary not only for fetal bone formation but also for maintaining the mother's bone density. Multiple childbirths do not carry only negative effects, however — studies have also reported that women with more births have a lower risk of hormone receptor-positive breast cancer and ovarian cancer.

"By comprehensively considering a woman's lifetime pregnancy and childbirth history alongside her hormonal exposure, we can assess fracture risk and use that as a basis for managing bone health through calcium and vitamin D intake during pregnancy and regular bone density screenings," Seong said. "I hope this research serves as an opportunity to more precisely identify those at high risk for osteoporosis and to continue conducting research that is of practical benefit to patient care."

Ha, who supervised the research, said the award was meaningful because a resident physician had taken the initiative to explore an important clinical question in bone metabolic disease using national big data. "I will continue to guide and support young researchers so they can actively participate in and produce results in osteoporosis and bone metabolic disease research," he added.