Introduction: Asthma, a common chronic condition during pregnancy, is associated with perinatal complications, and increases the likelihood that offspring will develop bronchiolitis and asthma. Obesity increases asthma exacerbation risk in pregnancy, and is an independent risk factor for wheeze and asthma in offspring.
Aims: In this secondary analysis of the Managing Asthma in Pregnancy study, we investigated interactions between maternal BMI and fractional exhaled nitric oxide (FENO)-based management, on asthma exacerbations in pregnancy, and offspring wheeze-related outcomes.
Methods: Pregnant women, recruited prior to 22 weeks’ gestation, were randomised to asthma treatment adjustment according to either symptoms (control group), or airway inflammation (assessed by FENO) and symptoms (FENO group). Exacerbations requiring medical intervention (hospital admission, ED presentation, unscheduled GP visit or course of oral corticosteroids) were recorded prospectively. A validated parent-completed questionnaire assessed wheeze related illnesses at ages 6 months, 12 months and 4-6 years.
Results: The proportion of women with exacerbations during pregnancy was higher in overweight (40.6%) and obese (47.8%) women, compared to non-overweight women (33.3%) in the control group. Similarly in the FENO group, the proportion of women with exacerbations was higher in the overweight (27.8%) and obese (31.0%) women compared to non-overweight women (15.2%). The FENO algorithm was less effective in reducing exacerbations with increasing BMI. Health care utilisation for wheeze in infancy occurred in 47.8% of infants of obese mothers in the control group (34.8% in the FENO group), 36.4% of infants of overweight mothers (16.7% in the FENO group) and 18.8% of infants of non-overweight mothers (9.5% in the FENO group).
Conclusion: FENO-based management for asthma during pregnancy was beneficial in all three BMI groups, however, obesity was associated with poorer maternal and infant outcomes. The best outcomes were found in non-overweight mothers randomised to the FENO-based management group, indicating the importance of pre-conception nutritional status in contributing to outcomes for pregnant women with asthma.