Objective To compare the time taken by preterm infants with evolving chronic lung disease to achieve full oral feeding when supported with humidified high flow nasal cannula (HFNC) or nasal continuous positive airway pressure (NCPAP).

Design Single centre randomised controlled trial.

Setting Level III neonatal intensive care unit at the Coombe Women and Infants University Hospital, Dublin, Ireland.

Patients Very low birthweight (birth weight <1500 g) infants born before 30 weeks' gestation who were NCPAP-dependent at 32 weeks corrected gestational age were eligible to participate.

Interventions Enrolled infants were randomised in a 1:1 ratio to receive HFNC or NCPAP. Participants were monitored daily until full oral feeding was established and the baby was off respiratory support.

Main outcome measures Our primary outcome was the number of days taken to establish full oral feeds (defined as oral intake ≥120 mL/kg/day) from the time of randomisation. We estimated that enrolling 44 subjects (22 in each group) would allow us demonstrate a 7-day difference in our primary outcome with 80% power and α of 5%.

Results Forty-four infants were randomised (22 to HFNC vs 22 to NCPAP). The mean time to achieve full oral feeding was not different between the groups (HFNC 36.5 (±18.2) days vs NCPAP 34.1 (±11.2) days, p=0.61).

Conclusions Preterm infants treated with HFNC did not achieve full oral feeding more quickly than infants treated with NCPAP.

Trial registration number ISRCTN66716753.