A large national dataset was used to examine whether OCS use during pregnancy influences the development of gestational diabetes. The study, published in Women’s Health, assessed all Korean pregnancies resulting in live births from 2010 to 2021.

The analysis included 1 325 940 eligible pregnancies, of which 79 710 (6.0%) had OCS exposure. A sequential landmark design evaluated exposure in 3-week intervals from weeks 1 to 27. Within each window, exposed and unexposed pregnancies were compared using overlap weighting to balance comorbidities, medication use, and health care utilization. Gestational diabetes was identified from 20 weeks plus one day using a validated claims algorithm. Risk ratios were estimated with 200-replicate bootstrapping, and subgroup analyses assessed potential modifying factors.

Most exposure windows showed no significant association with gestational diabetes. A slight risk elevation appeared only for exposure during weeks 4–6 (weighted RR 1.10, 95% CI 1.03–1.17). In pooled analyses, gestational diabetes occurred in 9.50% of exposed pregnancies versus 7.36% of unexposed pregnancies (weighted RR 1.01, 95% CI 0.99–1.03). Subgroup patterns were broadly consistent.

Overall, the findings suggest predominantly neutral metabolic effects, aside from a narrow early-pregnancy signal requiring further evaluation.