Occupational characteristics and high-risk pregnancy outcomes among Korean nurses: a secondary analysis of the Korea Nurses’ Health Study

Purpose: This study examined associations between multidimensional occupational characteristics and high-risk pregnancy outcomes among nurses. Methods: This cross-sectional secondary analysis used Korea Nurses’ Health Study data collected from 2015 to 2019. Occupational characteristics included shift work type, hospital bed size, overtime work, prolonged standing, heavy lifting, and emotional labor. Nine self-reported outcomes were assessed: preterm birth, preterm labor, preeclampsia/eclampsia, gestational diabetes mellitus, incompetent internal os of the cervix, placenta previa, placental abruption, oligohydramnios/polyhydramnios, and premature rupture of membranes. Multivariable logistic models simultaneously included demographic, occupational, and reproductive health factors; Firth penalization was used for sparse outcomes. Results: Among 1,330 nurses, 748 (56.2%) reported at least one high-risk pregnancy outcome. Frequencies did not differ significantly by shift work type. In adjusted models, emotional labor was associated with preterm labor; hospital bed size with gestational diabetes mellitus; heavy lifting with preterm birth and placental abruption; and standing time with preterm birth. Endometriosis history was associated with preterm labor, and uterine myoma history with preterm labor, preterm birth, and placenta previa. Conclusion: Selected occupational and reproductive health factors, rather than shift work type alone, were associated with high-risk pregnancy outcomes in the fitted models. Because occupational exposure timing may not have corresponded to the most recent pregnancy and the outcomes were self-reported, the findings require cautious interpretation and prospective confirmation before they guide pregnancy-specific risk assessment or work modification.