Maternal Asthma and Risk of Preterm Delivery

Abstract

Approximately 1% of pregnant women are asthmatic and the prevalence could be increasing, like it is in the general population. The authors used data from a nested case-control study to learn whether maternal asthma is associated with a greater risk of preterm labor and delivery. The study group included 312 women who delivered before 37 completed weeks gestation and, as a control group, 424 women who delivered a singleton infant at term. Women with a history of asthma were approximately twice as likely as others to have preterm delivery (odds ratio [OR], 2.03; 95% confidence interval [CI], 1.01-4.09). A slightly stronger association (OR, 2.37; 95% CI, 1.15-4.88) was evident after adjusting for maternal age, race/ethnicity, parity, Medicaid payment status, and smoking during pregnancy. Asthma correlated with a greater than 2-fold increase in risk of both spontaneous and medically induced preterm delivery, but the association was statistically significant only for the latter. Maternal asthma was associated with both moderate (34-36 weeks) and very (before 34 weeks) preterm deliveries. These findings point to an increased risk of preterm delivery in asthmatic women.