Impact of obesity on perinatal outcomes among asthmatic women

BACKGROUND: Only one study has investigated the combined effect of maternal asthma and obesity on perinatal outcomes; however, it did not consider small-for-gestational age and large-for-gestational age infants. OBJECTIVES: To examine the impact of obesity on perinatal outcomes among asthmatic women. METHODS: A cohort of 1386 pregnancies from asthmatic women was reconstructed using three of Quebec's administrative databases and a questionnaire. Women were categorized using their prepregnancy body mass index. Underweight, overweight and obese women were compared with normal weight women. The primary outcome was the birth of a small-for-gestational-age infant, defined as a birth weight below the 10th percentile for gestational age and sex. Secondary outcomes were large-for-gestational-age infants (birth weight >90th percentile for gestational age) and preterm birth (<37 weeks' gestation). Logistic regression models were used to obtain the ORs of having small-for-gestational-age infants, large-for-gestational-age infants and preterm birth as a function of body mass index. RESULTS: The proportions of underweight, normal weight, overweight and obese women were 10.8%, 53.3%, 19.7% and 16.2%, respectively. Obese asthmatic women were not found to be significantly more at risk for giving birth to small-for-gestational-age infants (OR 0.6 [95% CI 0.4 to 1.1]), large-for-gestational-age infants (OR 1.2 [95% CI 0.7 to 2.2]) or having a preterm delivery (OR 0.7 [95% CI 0.4 to 1.3]) than normal-weight asthmatic women. CONCLUSIONS: No significant negative interaction between maternal asthma and obesity on adverse perinatal outcomes was observed.