Abstract Background Inflammatory bowel disease (IBD) often affects women of reproductive age1. Maintaining disease control in the perinatal period is crucial to avoid adverse outcomes2,3. The 2025 Global Consensus guideline recommends continuing biologics throughout pregnancy4. However, more real-world data on biologic use patterns during pregnancy and associated outcomes are needed. This study assessed maternal and neonatal outcomes among women with IBD following different biologic use trajectories during pregnancy. Methods A retrospective study was performed using medical records from pregnant women with IBD, treated and/or delivering at our tertiary centre between 2017 and 2025. Disease activity in pregnancy was a composite variable based on the notification of clinical worsening, initiation of IBD medication, and/or delivery due to disease activity in the medical record. Patients were categorized into four groups based on biologics utilization in pregnancy: continuers, discontinuers, initiators or non-users. Results In total, 255 pregnancies were included: 103 were continuers, 68 discontinuers, 7 starters and 77 non-users. Maternal age and IBD subtype were similar across groups. Before conception, 67.1% used biologics. Disease activity in pregnancy was highest among initiators (100.0%), followed by discontinuers (27.9%), continuers (22.3%) and non-users (19.5%) (Table 1). Biologics were typically discontinued or initiated around 22 weeks’ gestation. Mean gestational age at delivery was 38 weeks 5 days. Preterm birth (37 weeks) occurred most in initiators (14.3%), then discontinuers (12.1%), continuers (8.1%) and non-users (3.2%). Low birthweight (2500g) was more frequent in initiators (14.3%), followed by continuers (9.3%), discontinuers (6.0%) and non-users (1.6%). In contrast, small for gestational age was most common in continuers (18.9%), followed by initiators (14.3%), discontinuers (9.0%) and non-exposed women (7.9%) (Table 2). C-section rates were highest in non-users (41.3%) and discontinuers (39.4%) compared to continuers (31.5%). Conclusion In this cohort from a specialized IBD clinic, women who discontinued biologics during pregnancy had higher rates of preterm birth, C-sections, and third-trimester disease activity compared to continuers, supporting the potential benefits of maintaining biologic therapy during pregnancy. However, the higher rate of SGA infants among continuers may reflect confounding by indication and warrants further research. All initiators presented with disease activity and had the highest rates of preterm birth and C-section, underscoring the importance of adequate disease control during pregnancy. References: Prentice RE, Flanagan EK, Wright EK, et al. Active Inflammatory Bowel Disease on Intestinal Ultrasound During Pregnancy Is Associated With an Increased Risk of Adverse Pregnancy and Neonatal Outcomes Independent of Clinical and Biochemical Disease Activity. Gastroenterology. Sep 2025;169(4):647–662. doi:10.1053/j.gastro.2025.03.016 Mahadevan U, Long MD, Kane SV, et al. Pregnancy and Neonatal Outcomes After Fetal Exposure to Biologics and Thiopurines Among Women With Inflammatory Bowel Disease. Gastroenterology. Mar 2021;160(4):1131–1139. doi:10.1053/j.gastro.2020.11.038 Julsgaard M, Hvas CL, Gearry RB, et al. Anti-TNF Therapy in Pregnant Women With Inflammatory Bowel Disease: Effects of Therapeutic Strategies on Disease Behavior and Birth Outcomes. Inflamm Bowel Dis. Jan 1 2020;26(1):93–102. doi:10.1093/ibd/izz110 Mahadevan U, Seow CH, Barnes EL, et al. Global Consensus Statement on the Management of Pregnancy in Inflammatory Bowel Disease. J Crohns Colitis. Sep 7 2025;19(8)doi:10.1093/ecco-jcc/jjaf129 Conflict of interest: Van Den Broeck, Elise: No conflict of interest De Dycker, Els: No conflict of interest Annaert, Zenobie: No conflict of interest Geens, Patricia: No conflict of interest Lambrechts, Tessy: No conflict of interest Loddewijkx, Elien: No conflict of interest Brödel, Sarah: No conflict of interest Van Calsteren, Kristel: No conflict of interest Lannoo, Lore: No conflict of interest Guedelha Sabino, João: J.S. is a senior clinical investigator of the Research Foundation Flanders (FWO) received speaker’s fees from Pfizer, Abbvie, Ferring, Falk, Takeda, Janssen, Fresenius, and Galapagos Consultancy fees from Pfizer, Janssen, Ferring, Fresenius, Abbvie, Galapagos, Celltrion, Pharmacosmos, and Pharmanovia and research support from Galapagos and Viatris. Verstockt, Bram: B.V. is supported by the Clinical Research Fund (KOOR) at UZ Leuven and the Research Council at KU Leuven received research support from AbbVie, Biora Therapeutics, Celltrion, Landos, Pfizer, Sossei Heptares, and Takeda received speaker’s fees from AbbVie, Biogen, Bristol Myers Squibb, Celltrion, Chiesi, Eli Lilly, Falk, Ferring, Galapagos, Johnson and Johnson, MSD, Pfizer, R-Biopharm, Sandoz, Takeda, Tillots Pharma, Truvion, and Viatris and received consultancy fees from AbbVie, Alfasigma, Alimentiv, Applied Strategic, AstraZeneca, Atheneum, BenevolentAI, Biora Therapeutics, Boxer Capital, Bristol Myers Squibb, Eli Lilly, Galapagos, Guidepont, Landos, Merck, Mylan, Nxera, Inotrem, Ipsos, Johnson and Johnson, Pfizer, Progenity, Sandoz, Sanofi, Santa Ana Bio, Sapphire Therapeutics, Sosei Heptares, Takeda, Tillots Pharma, and Viatris and lastly, holds stock options in Vagustim. Ferrante, Marc: M.F. reports Research grants from AbbVie, EG Pharma, Celltrion, Janssen, Phizer, Takeda and Viatris consultancy fees from AbbVie, AgomAb Therapeutics, Boehringer Ingelheim, Celgene, Celltrion, Eli Lilly, Janssen-Cilag, MRM Health, Merck Sharp and Dohme, Pfizer, Takeda and ThermoFisher and speakers’ fees from AbbVie, Biogen, Boehringer Ingelheim, Dr Falk Pharma, Ferring, Janssen-Cilag, Merck Sharp and Dohme, Pfizer, Takeda, Truvion Healthcare and Viatris. M.F. is a Senior Clinical Investigator of the Research Foundation Flanders (FWO), Belgium. Ceulemans, Michael: M.C. is supported by a Senior Postdoctoral Fellowship fundamental research of the Research Foundation Flanders (FWO, 1246425N) is coordinator of the BELpREG pregnancy registry in Belgium which received research grants from P&G Health, Tilman, UCB, Almirall, KelaPharma, Sanofi, and Johnson & Johnson and received speaker’s fees from UCB and KelaPharma, and a research grant from HRA Pharma. S.V. holds a BOF-KFO from the KU Leuven received lecture fees from AbbVie, Dr. Falk Pharma, Ferring, Hospira, MSD, Takeda and Tillotts consultancy fees from AbbVie, AbolerIS Pharma, Alimentiv, Arena, AstraZeneca, Avaxia, BMS, Boehringer Ingelheim, Celgene, CVasThera, Dr Falk Pharma, Eli Lilly, Ferring, Galapagos, Genentech/Roche, Gilead, Hospira, Imidomics, Janssen, Johnson and Johnson, Materia Prima, MiroBio, Morphic, MrMHealth, MSD, Mundipharma, Pfizer Inc., Prodigest, Progenity, Prometheus, Robarts Clinical Trials, Second Genome, Shire, Surrozen, Takeda, Theravance Biopharma, Tillots Pharma AG and Zealand Pharma and grant/research support from AbbVie, Galapagos, MSD, Pfizer Inc. and Takeda.
Broeck et al. (Thu,) studied this question.