ObjectiveTo identify risk factors associated with delivery room respiratory support in at-risk infants who are initially vigorous and received delayed cord clamping (DCC).DesignProspective cohort study.SettingTwo perinatal centres in Melbourne, Australia.PatientsAt-risk infants born at ≥35⁺⁰ weeks gestation with a paediatric doctor in attendance who were initially vigorous and received DCC for >60 s.Main outcome measuresDelivery room respiratory support defined as facemask positive pressure ventilation, continuous positive airway pressure and/or supplemental oxygen within 10 min of birth.ResultsTwo hundred and ninety-eight infants born at a median (IQR) gestational age of 39⁺³ (38⁺²–40⁺²) weeks were included. Cord clamping occurred at a median (IQR) of 128 (123–145) s. Forty-four (15%) infants received respiratory support at a median of 214 (IQR 156–326) s after birth. Neonatal unit admission for respiratory distress occurred in 32% of infants receiving delivery room respiratory support vs 1% of infants who did not receive delivery room respiratory support (p<0.001). Risk factors independently associated with delivery room respiratory support were average heart rate (HR) at 90–120 s after birth (determined using three-lead ECG), mode of birth and time to establish regular cries. Decision tree analysis identified that infants at highest risk had an average HR of <165 beats per minute at 90–120 s after birth following caesarean section (risk of 39%). Infants with an average HR of ≥165 beats per minute at 90–120 s after birth were at low risk (5%).ConclusionsWe present a clinical decision pathway for at-risk infants who may benefit from close observation following DCC. Our findings provide a novel perspective of HR beyond the traditional threshold of 100 beats per minute.