Influence of maternal body mass index and gestational weight gain, with asthma management on maternal and infant outcomes

Asthma is a common condition in preganncy and associated with perinatal complications and respiratory illness in offspring. This secondary analysis of an RCT investigated the influence of maternal body mass index (BMI) and gestational weight gain (GWG) and fractional exhaled nitric oxide (FeNO)-based management, on asthma exacerbations in pregnancy and wheeze-related outcomes in offspring. Women were randomised prior to 22 weeks gestation to asthma treatment adjustment according to symptoms (control group) or FeNO and symptoms (FeNO group). Exacerbations requiring medical intervention were recorded prospectively. Height and weight were measured at baseline, and in late pregnancy for a sub-group of women. Wheeze in infancy was determined by parent report. The incidence rate ratio (IRR) for maternal exacerbations was different between management groups for non-obese mothers (0.42, 95%CI 0.33-0.76, p=0.004, n=129) and women with GWG within recommendations (0.28, 95%CI 0.10-0.75, P=0.012, n=43), but not for obese mothers (0.59, 95%CI 0.32-1.09, P=0.09, n=88), or women with excess GWG (0.58, 95%CI 0.32-1.04, P=0.07, n=104). Recurrent bronchiolitis occurred in 5.3% of infants born to non-overweight mothers, 16.7% of infants of overweight mothers and 21.7% of infants of obese mothers in the control group. In the FeNO group, only 2 infants of obese mothers had recurrent bronchiolitis (7.1%, P=0.031). FeNO-based management reduces exacerbations in pregnancy and infant bronchiolitis, but these effects are attenuated among obese mothers and those with excess GWG, indicating the importance of weight management in contributing to improved asthma management in pregnancy.