Maternal and neonatal outcomes in women with inflammatory bowel disease following different biologic utilization trajectories in pregnancy

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Objective The 2025 Global Consensus recommends continuing biologics throughout pregnancy in women with inflammatory bowel disease. Real-world evidence on biologic treatment patterns and outcomes remains limited. This study compared maternal and neonatal outcomes across different biologic use trajectories during pregnancy. Methods This retrospective study included pregnant women with inflammatory bowel disease treated or delivering at University Hospitals Leuven, Belgium, between 2017 and 2025. Patients were categorized as biologic continuers, discontinuers, non-users, or initiators during pregnancy. Results Among 211 pregnancies, 75 (35.5%) were continuers, 66 (31.3%) discontinuers, 63 (29.9%) non-users, and seven (3.3%) initiators. Before conception, 66.8% ( N = 211) used biologics. Third-trimester disease activity occurred in 42.9% of initiators (3/7), 19.7% of discontinuers (13/66), 18.7% of continuers (14/75), and 17.5% of non-users (11/63). C-sections occurred more in non-users (41.3%, 26/63) and discontinuers (39.4%, 26/66), than in continuers (31.1%, 23/74). Preterm birth was more common among initiators (14.3%, 1/7) and discontinuers (12.1%, 8/66) than continuers (8.0%, 6/75) and non-users (3.2%, 2/62). Low birthweight occurred most in initiators (14.3%, 1/7), continuers (8.1%, 6/74), and discontinuers (6.1%, 4/66). Small-for-gestational-age was numerically more frequent among continuers (14.9%, 11/74) and initiators (14.3%, 1/7), than discontinuers (7.6%, 5/66) and non-users (6.5%, 4/62) ( P = 0.21). Conclusions Discontinuers had numerically more C-sections, preterm births, and third-trimester disease activity than continuers. The numerically higher small-for-gestational-age rate among continuers warrants further investigation. Initiators showed the poorest outcomes, highlighting the need for adequate disease control before and during pregnancy. Larger, confounder-adjusted studies are needed to clarify the relationship between biologic use, disease activity, and outcomes.