Background/objectives: It has been reported that adverse fetal outcomes are more prevalent in pregnant women with asthma than they are in women without asthma. In our study, we investigated the effect that the severity of asthma during pregnancy has on the risk of a small for gestational age (SGA) infant, low birth weight (LBW), and preterm birth.
Methods: A population-based cohort of 13,007 pregnancies from asthmatic women was reconstructed through the linking of three of Quebec's (Canada) administrative databases covering the period between 1990 and 2002. A two-stage sampling cohort design was used to collect additional information on the selected women's life-style habits via a mailed questionnaire. Asthma severity during pregnancy was measured with a validated database index. A logistic regression model was used to obtain the adjusted odds ratios of SGA, LBW and preterm birth as a function of the level of asthma severity.
Results: The proportions of women with mild, moderate and severe asthma were 82.5%, 12.5% and 5.0%, respectively. We sent 3,168 questionnaires to selected women, with a 40.2% (n=1274) response rate. Final estimates showed that the risk of SGA was significantly higher among severe (OR:1.48, 95%CI: 1.15-1.91) and moderate asthmatic women (OR: 1.30, 95%CI:1.10-1.55) than mild asthmatic women. No significant associations were found between asthma severity, preterm birth and LBW.
Conclusions: Mothers with severe and moderate asthma during pregnancy have a higher risk of SGA babies than those with mild asthma.