A population-based case-control study on the effect of bronchial asthma during pregnancy for congenital abnormalities of the offspring.

Bronchial asthma is one of the most common maternal diseases complicating pregnancy. We assessed the risks of congenital abnormalities in a case-control population-based analysis using the dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities between 1980 and 1996. Of the 22,843 cases with congenital abnormalities, 511 (2.2%) had mothers with bronchial asthma, while of the 38,151 matched control subjects without congenital abnormalities 757 (2.0%) had mothers with bronchial asthma (unadjusted prevalence odds ratios [POR] 1.2; 95% CI: 1.0-1.3). In all mothers with bronchial asthma, a higher incidence of respiratory tract infections and higher drug intake could be observed. In the case group of medically recorded bronchial asthma, a slightly increased risk for club foot has been revealed. However, this weak association could be explained by the higher proportion of preterm births in this group. The main limitation of the analysis was that at the time of data collection only a small proportion of pregnant mothers were using anti-asthma medications recommended by the actual guidelines.