Rationale<br>Data regarding maternal and fetal outcomes for many asthma medications are insufficient.<br><br>Methods<br>EXPECT is an ongoing prospective, observational study of pregnant women exposed to ?1 dose of omalizumab within 8 weeks prior to conception or at any time during pregnancy. Data on mother and pregnancy/infant are collected at enrollment, each trimester of pregnancy, pregnancy outcome, and up to 18 months post-delivery. Maternal asthma severity is assessed by mother’s health provider. Data collected: rates of live births, spontaneous abortions, elective terminations, stillbirths, birth weight, gestational age, and congenital anomalies. Data are from an annual cumulative summary including September 29, 2006 -November 30, 2013.<br><br>Results<br>Of 207 prospectively enrolled pregnancies, outcomes from 186 pregnancies were reported. Asthma severity was available for 164 women: mild (4/164, 2.4%), moderate (55/164, 33.5%), severe (105/164, 64.0%). There were 174 live births of 178 infants (4 twin pairs), 8 spontaneous abortions, 2 fetal deaths/stillbirths and 2 elective terminations. Of 170 singleton infants, 24 (14.1%) were born prematurely (<37 weeks) and of these 3 (12.5%) were considered small for gestational age (SGA, weight <10thpercentile for gestational age). Of 140 singleton full-term infants with weight data, 4 (2.9%) had low birthweight (<2500 g) and 16 (11.4%) were considered SGA. Overall, 27 (15.2%) infants had confirmed congenital anomalies. Eleven (6.2%) infants had a major birth defect; omalizumab exposure occurred in the first trimester in all cases. No pattern of anomalies was observed.<br><br>Conclusions<br>Given the small sample size and severity of maternal asthma, these pregnancy outcomes are not inconsistent with previous observations.