Vasa previa and extreme prematurity: a population-based study.

OBJECTIVE: To determine population-based risks of preterm birth associated with vasa previa.

STUDY DESIGN: Included were 945,950 singleton, live birth cesarean deliveries with and without vasa previa (gestational ages 24-41 weeks) in California between 2007 and 2012. Odds ratios (ORs) of preterm birth were estimated using logistic regression.

RESULTS: In total, 586 were complicated by vasa previa (0.06%). In total, 369 (63%) of those with vasa previa were delivered <37 weeks, compared with 91,662 (10%) of those without. Odds of extreme and very preterm birth were substantially higher for pregnancies with vasa previa even after controlling for comorbidities known to contribute to prematurity, with ORs of 4.6 (95% confidence interval, CI: 1.7-12.5) and 16.0 (95% CI: 10.3-24.8), respectively.

CONCLUSION: Based on these population-based data, most patients with vasa previa are delivered between 32 and 36 weeks gestation; however, a clinically significant portion occur before 32 weeks. These data are helpful in counseling patients with vasa previa regarding prematurity risk.