Prevalence of pregnancy and birth outcomes following biologic exposure in immune‐mediated inflammatory diseases: A population‐based study

AIMS: Almost 5% of pregnancies are affected by immune-mediated inflammatory diseases (IMIDs). As treatments become available, understanding their use during pregnancy is important. We aimed to describe maternal, pregnancy and infant outcomes among IMID pregnancies exposed to biologic therapies. METHODS: Using the Merative™ MarketScan® Commercial Database, we identified pregnancies among mothers aged 15-45 with a pre-gestational IMID diagnosis. Biologic exposure during pregnancy was ascertained using prescription and procedure claims and classified by trimester. Outcomes included maternal complications, fetal/neonatal outcomes and pregnancy loss. Descriptive statistics were used to summarize characteristics, comorbidities, medication use and outcomes by biologic exposure status. RESULTS: Among 257 409 IMID pregnancies, 6531 (2.5%) were exposed to biologics. Biologic-exposed pregnancies more frequently involved multiple IMIDs (34.9% vs. 7.7%). Nearly half of tumour necrosis factor inhibitor (TNFi) exposures occurred across all trimesters, while first-trimester-only exposure was more common for several non-TNFi biologics. Live births occurred in 77.4% of biologic-exposed pregnancies and 74.2% of biologic-unexposed pregnancies, with most births occurring at term. Maternal serious infections (i.e., infections requiring hospitalization) occurred in 19.7% of biologic-exposed pregnancies and 16.5% of unexposed pregnancies. Among 2066 biologic-exposed infants, the proportions of low birth weight and neonatal intensive care unit admission varied by specific non-TNFi biologics, whereas the distribution of neonatal outcomes appeared similar across exposure groups. CONCLUSION: Biologic use in IMID pregnancy increased over time and extended beyond the first trimester. Pregnancies with biologic exposure differed from unexposed pregnancies in disease characteristics and treatment patterns. Maternal and neonatal outcomes varied across biologic exposure groups.