The Xolair Pregnancy Registry (EXPECT): Perinatal outcomes among pregnant women with asthma treated with omalizumab (Xolair) compared against those of a cohort of pregnant women with moderate-to-severe asthma

The EXPECT pregnancy registry was a prospective observational study established in 2006 to evaluate perinatal outcomes in women exposed to omalizumab during pregnancy. Because asthma in pregnant women itself is associated with adverse perinatal outcomes, the final EXPECT results were compared against a cohort of pregnant women with moderate-to-severe asthma unexposed to omalizumab. 250 women exposed to omalizumab during their pregnancy were enrolled in EXPECT, and perinatal outcomes were collected up to 18 months after delivery. The disease-matched external comparator cohort of pregnant women not exposed to omalizumab (n=1,153), the Quebec External Comparator Cohort (QECC), was created using data from healthcare databases, and outcome estimates were age-adjusted to the age distribution of the EXPECT cohort. Among singleton infants in EXPECT, the prevalence of major congenital anomalies was 8.1% (18/223), similar to that in QECC (8.9%). In EXPECT, 99.1% of pregnancies led to a live birth and 0.9% ended in at least one fetal death/stillbirth, similar to the 99.3% and 0.9%, respectively, found in QECC. Premature birth and small for gestational age (SGA) were identified in 15.0% and 9.7% of EXPECT infants, respectively, and 11.3% and 15.8%, respectively, in QECC. Although this study cannot definitively establish the absence of any increased risk with omalizumab, there was no evidence of an increased risk of major congenital anomalies following exposure to omalizumab among pregnant women compared to a disease-matched cohort of pregnant women with moderate-to-severe asthma.