There are no data describing how very preterm infants breathe spontaneously immediately after birth. We studied a convenience sample of spontaneously breathing infants <or=32 wk' gestation treated with facemask continuous positive airway pressure at birth. Airway pressure and flow were measured and each breath analyzed. Twelve infants had 792 breaths suitable for analysis. Results are given as mean (SD). Gestational age and birth weight were 29 (1.9) wk and 1220 (412) g. Recordings were started 159 (77) s after birth. The inspiratory pattern and duration was similar in all breaths at 0.36 (0.11) s. There were five expiratory patterns; most infants had more than one. In 79% of breaths expiratory duration (1.6 (1.1) s) was slowed or held by interruption or braking of expiratory flow. It was braked in 47% to a complete expiratory hold, in 22% by grunting or crying, and in 10% by slow or interrupted expiration. In 21% of the breaths, expiration was not interrupted and lasted 0.53 (0.13) s. Half of these breaths represented a panting pattern (rate >60 /min). Immediately after birth, most very preterm infants, treated with continuous positive airway pressure, frequently prolong their expiration by braking the expiratory flow. BACKGROUND :