Anti-Tumor Necrosis Factor Therapy and the Risk of Gestational Diabetes in Pregnant Women with Inflammatory Bowel Disease

Introduction: Anti-tumor necrosis factor (anti-TNF) therapy may improve insulin sensitivity, and its impact during pregnancy remains unclear. We aimed to assess the risk of gestational diabetes mellitus (GDM) associated with anti-TNF treatment among pregnant women with inflammatory bowel disease (IBD). Methods: This nationwide cohort study included patients with IBD in Korea from 2010 to 2021. Anti-TNF exposure was identified from the last menstrual period (LMP) to LMP+140 days. The development of GDM was assessed from LMP+141 days to delivery. We performed overlap weighting to balance the covariates and used a generalized linear mixed model to measure the risk ratio (RR) and 95% confidence intervals (CIs). The anti-TNF group was compared with the unexposed group, as well as with the immunosuppressant, 5-aminosalicylate, and untreated groups. Results: A total of 3,695 pregnancies in women with IBD were identified, of which 338 (9.2%) were exposed to anti-TNFs. GDM was found in 7.1% of the pregnancies exposed to anti-TNFs as compared with 11.0% of those unexposed. The crude and weighted RR for GDM risk were 0.64 (95% CI 0.43–0.96) and 0.68 (0.55–0.84), respectively. The weighted RR when compared with the immunosuppressant, 5-aminosalicylate, and untreated groups were 0.70 (0.41–1.18), 0.71 (0.52–0.95), and 0.85 (0.59–1.24), respectively. Discussion: This nationwide cohort reported a decreased risk of GDM among patients who used anti-TNFs during early pregnancy compared to those unexposed. GDM risk may become a consideration in the decision-making process when choosing treatment options for pregnant women with a risk factor for GDM.