Table 1

Baseline characteristics and covariates

All newborns
(n=17 848)*
Included newborns
(n=434)*
ICC†
Delivery modeCaesarean section3937 (23%)215 (50%)
Standard vaginal13 331 (76%)194 (45%)
Breech162 (0.9%)24 (6%)
Vacuum39 (0.2%)1 (0.2%)
Other14 (0.1%)
Females8167 (47%)168 (39%)
Gestational age (weeks)38 (37–40)38 (37–40)
Gestational age <36 weeks594 (3.3%)29 (7%)
Birth weight (g)3248 ± 5353074 ± 593
Apgar 1 min9 (9–9)6 (5–7)
Apgar 5 min10 (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 ECO2 >2% (s)10.0 (3.1–34.9) ‡
No of ventilation sequences5 (2–8)
Duration of ventilation sequences (s)29 ± 46§ / 18 (11 - 30)¶0.15
Expired volume, VTE (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
ECO2 (% of expired air) ¶2.9 ± 2.2 § / 2.9 (1.3–4.1)¶0.50
Max ECO2 in first 5 min of BMV7.2 ± 2.8
Initial ECO2 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 ECO2 >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; ECO2, expired carbon dioxide.