(278) Maternal and Infant Outcomes Following Infliximab Exposure During Pregnancy

Background: Infliximab is approved for the treatment of several rheumatic, dermatologic and gastroenterologic diseases. There are limited data on the safety of infliximab use during pregnancy.

Objectives: The objective of this study was to compare the frequency of maternal and infant adverse outcomes in pregnant persons treated with infliximab to pregnant persons with the same underlying conditions but not treated with infliximab.

Methods: Between 2004 and 2023, MotherToBaby Pregnancy Studies at the University of California San Diego, conducted a U.S. and Canada-based observational prospective cohort study on pregnancy outcomes in persons with various autoimmune diseases. From this dataset, pregnant persons were selected who received at least 1 dose of infliximab from 3 months prior to and up to the end of pregnancy. This group was frequency matched 2:1 by the mother’s primary underlying disease to pregnant persons in the same dataset who had not been treated with infliximab. Data had been collected throughout pregnancy and 1 year postpartum through maternal interviews, medical record abstraction, and dysmorphology exams for minor malformations. The birth prevalence of major congenital malformations, incidence of patterns of minor malformations, spontaneous abortion, preterm delivery, and pre and postnatal growth deficiency were compared between exposed and unexposed groups. Poisson and Cox regression analyses were performed to compute crude and adjusted relative risks or hazard ratios (RR, aRR, HR) and their 95% Confidence Intervals (CI) considering selected confounders in each analysis.

Results: The sample was comprised of 222 infliximab-exposed and 444 unexposed pregnancies, of which 33 (5.0%) were lost-to-follow-up. Among live births, 7/189 (3.7%) of the infliximab-exposed had a major malformation compared to 35/404 (8.7%) in the unexposed group (aRR=0.5, 95% CI 0.2, 1.2). In the infliximab group, 24/204 (11.8%) delivered preterm ( < 37 weeks’ gestation) compared to 43/404 (10.6%) in the comparison group (aRR=0.9, 95% CI: 0.5, 1.6). Among the infliximab group, 7/153 (4.6%) resulted in spontaneous abortion compared to 10/335 (3.0%) in the comparison group (aHR=2.4, 95% CI: 0.9, 6.4). A specialized dysmorphology exam was completed for 306 infants; no specific pattern of minor anomalies was identified in the infliximab group. The proportion of infants with pre- or postnatal growth deficiency did not differ between groups.

Conclusions: No significant increased risks for major congenital malformations, preterm delivery or growth deficiency were identified in the infliximab-exposed group and there was no evidence of a pattern of minor malformations. These data are reassuring.