All newborns (n=17 848)* | Included newborns (n=434)* | ICC† | ||

Delivery mode | Caesarean section | 3937 (23%) | 215 (50%) | – |

Standard vaginal | 13 331 (76%) | 194 (45%) | – | |

Breech | 162 (0.9%) | 24 (6%) | – | |

Vacuum | 39 (0.2%) | 1 (0.2%) | – | |

Other | 14 (0.1%) | – | ||

Females | 8167 (47%) | 168 (39%) | – | |

Gestational age (weeks) | 38 (37–40) | 38 (37–40) | – | |

Gestational age <36 weeks | 594 (3.3%) | 29 (7%) | – | |

Birth weight (g) | 3248 ± 535 | 3074 ± 593 | – | |

Apgar 1 min | 9 (9–9) | 6 (5–7) | – | |

Apgar 5 min | 10 (10–10) | 10 (8–10) | – | |

First detected heart rate (bpm) | – | 73 ± 21 | – | |

Time from birth to first ventilation (s) | – | 112 (78–158) | – | |

Time from first to last ventilation (s) | – | 184 (80–394) | – | |

Time to ECO_{2} >2% (s) | – | 10.0 (3.1–34.9) ‡ | – | |

No of ventilation sequences | – | 5 (2–8) | – | |

Duration of ventilation sequences (s) | – | 29 ± 46§ / 18 (11 - 30)¶ | 0.15 | |

Expired volume, V_{TE} (mL/kg) | – | 7.9 ± 6.4§ / 6.7 (4.1–11.0)¶ | 0.52 | |

Ventilation frequency (BMVs/min) | – | 52 ± 24§ / 47 (38–65)¶ | 0.62 | |

Mask leak (%)¶ | – | 44 ± 29§ / 40 (25–59)¶ | 0.40 | |

Peak inflation pressure (mbar)¶ | – | 35 ± 11§ / 38 (25–60)¶ | 0.54 | |

ECO_{2} (% of expired air) ¶ | – | 2.9 ± 2.2 § / 2.9 (1.3–4.1)¶ | 0.50 | |

Max ECO_{2} in first 5 min of BMV | – | 7.2 ± 2.8 | – | |

Initial ECO_{2}
| – | 0.9 (0.3–3.3) | – |

*Frequencies are given in the form of n (%), parameters with skewed distributions are given as median (25th quartile, 75th quartile), normally distributed parameters as mean±SD. For ventilation factors with repeated measurements per newborn, we report both means calculated by unconditional random intercept analysis and medians of medians.

†ICC—intercorrelation coefficient: proportion of total variance assigned to variance between patients.

‡Newborns who had ECO

_{2}>2% in the first ventilation (n=113) or did not reach threshold (n=23) not included.§Mean in first 5 min of BMV, SD is given as √total variance where the total variance is the sum of variance between and within patients.

¶Median of medians in first 5 min of BMV.

BMV, bag-mask ventilation; ECO

_{2}, expired carbon dioxide.