Identification of modifiable risk factors to prevent atopic wheeze in infants born to mothers with asthma: a cohort study.

OBJECTIVE: Maternal asthma is the leading risk factor for children developing wheeze and allergic disease in early life. We aimed to describe atopic phenotypes in infants of mothers with asthma and assess which early-life factors were associated with these phenotypes. METHODS: Participants were part of the Breathing for Life Trial Birth Cohort, which recruited pregnant women with asthma prior to 23 weeks gestation (n=549). Parents completed a validated questionnaire about their child's wheeze requiring healthcare utilisation (hospitalisation, emergency department visits, consultant referral and primary care visits for wheeze, asthma medication use), respiratory infections, eczema and rhinitis at 12 months of age. Latent class analysis was used to identify the atopic phenotypes among infants. Logistic regression assessed early-life risk factors including maternal characteristics, perinatal factors and environmental exposures. RESULTS: Three phenotypes were identified: low-atopy/low-wheeze (35.2%), atopic mild-wheeze (38.6%) and atopic high-wheeze (26.2%). Maternal obesity (aOR 3.22 95% CI 1.90, 5.44), smoking in pregnancy (aOR 2.60 95%CI 1.36, 4.97), asthma exacerbations in pregnancy (aOR 1.98 95%CI 1.30, 3.02), preterm birth (aOR 2.50 1.34, 4.66), and NICU admission (aOR 2.71 95%CI 1.14, 6.46) were associated with atopic high-wheeze compared to low-atopy/low-wheeze. Maternal obesity (aOR 2.02 95%CI 1.26, 3.24) and smoking in pregnancy (aOR 2.55 95%CI 1.37, 4.72) were associated with atopic mild-wheeze compared to low-atopy/low-wheeze. CONCLUSION: Multiple modifiable factors (maternal obesity, smoking and maternal asthma exacerbations) and adverse birth outcomes are associated with the severity of wheeze in infants of mothers with asthma, providing an opportunity for intervention to prevent later childhood asthma.