High risk of spontaneous preterm birth among infants with gastroschisis.

We examined the association between gastroschisis and preterm birth (PTB, <37 weeks) by subtype. The sample was drawn from singleton live births in California from 2007 to 2012 contained in a birth cohort file maintained by the California Office of Statewide Health Planning and Development (n = 2,891,965; 1,421 with gastroschisis). Relative risks (RRs) and 95% confidence intervals (CIs) were calculated for PTB by gestational age (<34, 34-36, and any <37 weeks) and by type (spontaneous labor with intact membranes, preterm premature rupture of the membranes [PPROM], provider initiated) and were adjusted for maternal characteristics. Over 44.5% of infants with gastroschisis were born preterm because of spontaneous etiologies; notably, 8.4% of infants with gastroschisis were born <34 weeks because of spontaneous etiologies (adjusted RRs 9.1-12.2). Overall, 53.7% of infants with gastroschisis were born preterm compared with only 6.9% of infants without gastroschisis (adjusted RR 15.2, 95% CI 13.6-19.5) and are at particularly high risk of spontaneous PTB. Nearly 9% of infants with gastroschisis delivered <34 weeks, regardless of preterm etiology, indicating that these infants are at great risk for PTB morbidities in addition to the complications from gastroschisis.