Late Breaking Abstract - Management of asthma in pregnancy using fractional exhaled nitric oxide (FENO) to adjust inhaled corticosteroid (ICS) dose did not improve perinatal outcomes: the Breathing for Life Trial (BLT)

Background: Asthma exacerbations in pregnancy are associated with adverse perinatal outcomes. FENO-based management in pregnancy reduced asthma exacerbations in a previous trial. BLT examined whether FENO-based asthma management would improve perinatal outcomes. Methods: BLT was a multi-centre, parallel group, RCT of asthma management guided by a FENO algorithm versus usual care. 1200 pregnant women with doctor diagnosed asthma and symptoms, or medication use for asthma in the previous year, were randomised to usual care (baseline assessment of asthma and no treatment changes) or FENO-based management. In the intervention group, a modified FENO algorithm was applied each 6-12 weeks (FENO used to adjust ICS dose, long acting beta agonist added when symptoms uncontrolled). A composite adverse perinatal outcome (preterm birth, intrauterine growth restriction, perinatal mortality, neonatal hospitalisation) was assessed from hospital records (primary outcome). Exacerbations in pregnancy (admission, emergency department visit, unscheduled doctor visit or oral steroid course) were assessed postpartum. Results: Baseline characteristics were similar between usual care (n=599) and FENO (n=601) groups. Intention to treat analysis found no significant difference between groups for the composite perinatal outcome (25.6% usual care, 29.4% FENO, OR 1.21 [0.94, 1.56]), all components of the composite outcome, and maternal exacerbations (19.2% usual care, 16.1% FENO, OR 0.80 [0.58, 1.10]). Conclusion: FENO-guided asthma management had no effect on perinatal outcomes. Funding: NHMRC Australia