Adverse outcomes in pregnancies of asthmatic women: results from a Canadian population.

Purpose: There has been little attention paid to asthma complicating pregnancy. This study is among the few studies that investigated this issue in a large Canadian population (more than two millions of Canadian pregnant women).

Methods: We carried out a historical cohort study using hospital discharge data collected by the Canadian Institute for Health Information for fiscal years 1989/90 to 1995/96.

Results: A total 2,017,553 obstetric deliveries were included in the analysis. Overall prevalence of asthma among these Canadian women were 0.43%, yielding a total of 8672 cases of asthmatic mothers. Maternal asthma was associated with all of the adverse pregnancy outcomes examined (including fetal death, preterm labour, hypertensive disorders of pregnancy, gestational diabetes, antepartum hemorrhage, infection of the amniotic cavity, premature rupture of membrane, cesarean delivery, as well as postpartum hemorrhage), and adjustment for important confounding factors by multiple logistic regression analysis did not change the overall results. These associations were consistently observed in teenage and adult mothers, although the associations in teenage mothers tended to be stronger than in adult mothers.

Conclusions: This study confirms that pregnant women with asthma are at substantially increased risk for many adverse pregnancy outcomes. For this reason, pregnant women with asthma are a particularly high-risk group to which extra attention, including increased efforts at education, monitoring, and optimal asthma management, may be appropriate.