Evaluating the association between omalizumab use and adverse fetal outcomes among pregnant women with asthma: a population-based retrospective cohort study

OBJECTIVE: This study aimed to evaluate the association between omalizumab use during pregnancy and the risk of adverse fetal outcomes among pregnant women with asthma. METHODS: This population-based retrospective cohort study was conducted using data from the 2010-2022 National Health Insurance Research Database and the Birth Certification Application in Taiwan. The study population was pregnant women with asthma. An active-comparator design was employed. Pregnant women who received at least one dose of omalizumab during pregnancy were assigned as the exposure group, while those having at least one prescription for inhaled corticosteroid (ICS) during pregnancy were assigned as the control group. The study outcome was adverse fetal outcomes. Propensity score matching was used to adjust for measurable confounders. Conditional logistic regression models were used to estimate the risk of adverse fetal outcomes. RESULTS: A total of 4,416 pregnant women with asthma were included, with 16 (0.1%) receiving omalizumab and 4,410 (99.9%) using ICS during pregnancy. The risk of adverse fetal outcomes, including pre-term birth (OR, 1.74; 95% CI, 0.46-6.63), low birth weight (OR, 1.04; 95% CI, 0.22-4.87), small for gestational age (OR, 1.11; 95% CI, 0.14-8.98), did not differ between omalizumab and ICS users. CONCLUSIONS: Omalizumab was not associated with an increased risk of adverse fetal outcomes among pregnant women with asthma. Further investigation with a larger sample of omalizumab users is warranted.