A sustained inflation (SI) at birth in preterm babies may be ineffective unless the infants breathe. Gain in lung volume is associated with breathing during delivery room non-invasive management. To describe the breathing patterns of preterm infants during an SI and correlate to a calculated gain in lung volume. Retrospective observational study. Data collected from a respiratory function monitor during SI (25 cmH2O for 15 s then PEEP at 5 cmH2O) through a face mask in preterm infants (gestational age [GA] ≤31 weeks). Spontaneous breaths, inspiratory time (TI), inspiratory/expiratory tidal volume (Vti/Vte), and gain in lung volume were determined. 30 SIs in 20 infants (mean GA 27 weeks; birth weight 825 g) were analysed and stratified in 2 groups according to spontaneous breathing: SIs without spontaneous breaths (apnoea: n = 11) and SIs with spontaneous breaths (breathing: n = 19). Mean GA was lower in the apnoea group versus the breathing group (25 vs. 27+5 weeks; p = 0.01). Mean birth weight was lower in the apnoea group versus the breathing group (683 vs. 860 g; p = ns). In the breathing group, the mean number of spontaneous breaths was 4 with a mean TI of 0.52 min, the mean Vti/kg was 5.9 mL/kg, and the mean Vte was 2.7 mL/kg. The calculated mean gain in lung volume was 7.5 mL/kg in the apnoea group and 17.8 mL/kg in the breathing group (p = 0.039). Actively breathing infants during an SI at birth showed a gain in lung volume higher than apnoeic infants. Spontaneous breathing during SI seems to be related to GA.