BACKGROUND: The Observational Study of the Use and Safety of Xolair (omalizumab) during Pregnancy (EXPECT) pregnancy registry was a prospective observational study established in 2006 to evaluate perinatal outcomes in pregnant women exposed to omalizumab and their infants.
OBJECTIVE: This analysis compares EXPECT outcomes with those from a disease-matched population of pregnant women not treated with omalizumab. Data from a substudy of platelet counts among newborns are also presented.
METHODS: The EXPECT study enrolled 250 women with asthma exposed to omalizumab during pregnancy. The disease-matched external comparator cohort of women with moderate-to-severe asthma (n = 1153), termed the Quebec External Comparator Cohort (QECC), was created by using data from health care databases in Quebec, Canada. Outcome estimates were age adjusted based on the maternal age distribution of the EXPECT study.
RESULTS: Among singleton infants in the EXPECT study, the prevalence of major congenital anomalies was 8.1%, which was similar to the 8.9% seen in the QECC. In the EXPECT study 99.1% of pregnancies resulted in live births, which was similar to 99.3% in the QECC. Premature birth was identified in 15.0% of EXPECT infants and 11.3% in the QECC. Small for gestational age was identified in 9.7% of EXPECT infants and 15.8% in the QECC.
CONCLUSION: There was no evidence of an increased risk of major congenital anomalies among pregnant women exposed to omalizumab compared with a disease-matched unexposed cohort. Given the observational nature of this registry, however, an absence of increased risk with omalizumab cannot be definitively established.