Objective To investigate the occurrence and duration of oxygen saturation (SpO₂) ≥95%, after extra oxygen for apnoea, bradycardia, cyanosis (ABC), and the relation with the duration of bradycardia and/or SpO₂ ≤80%.

Methods All preterm infants <32 weeks’ gestation supported with nasal continuous positive airway pressure (nCPAP) admitted to our centre were eligible for the study. We retrospectively identified all episodes of ABCs. In ABCs where oxygen supply was increased, duration and severity of bradycardia (<80 bpm), SpO₂ ≤80%, SpO₂ ≥95% and their correlation were investigated.

Results In 56 infants, 257 ABCs occurred where oxygen supply was increased. SpO₂ ≥95% occurred after 79% (202/257) of the ABCs, duration of extra oxygen supply was longer in ABCs with SpO₂ ≥95% than without SpO₂ ≥95% (median (IQR) 20 (8–80) vs 2 (2–3) min; p<0.001)). The duration of SpO₂ ≥95% was longer than bradycardia and SpO₂ ≤80% (median (IQR) 13 (4–30) vs 1 (1–1) vs 2 (1–2) min; p<0.001). SpO₂ ≥95% lasted longer when infants were in ambient air than when oxygen was given before the ABC occurred (median (IQR)15 (5–38) min vs 6 (3–24) min; p<0.01).

Conclusions In preterm infants supported with nCPAP in the neonatal intensive care unit (NICU), SpO₂ ≥95% frequently occurred when oxygen was increased for ABCs and lasted longer than the bradycardia and SpO₂ ≤80%.