Participant characteristics and clinical outcomes
| Participant characteristics | All infants | Any respiratory support | No respiratory support | P value |
| N=298 | n=44 | n=254 | ||
| Hospital at birth, n (%) | – | |||
| Royal Women’s Hospital | 253 (84) | 42 (95) | 211 (83) | |
| Monash Medical Centre | 45 (16) | 2 (5) | 43 (17) | |
| Maternal age (years) | 33 (30–35) | 33 (30–36) | 32 (30–35) | – |
| Primiparity, n (%) | 214/277 (77) | 36/43 (84) | 178/234 (76) | – |
| Gestational age (weeks+days) | 39+3 (38+3–40+3) | 39+2 (38+1–40+0) | 39+3 (38+3–40+4) | – |
| Birth weight (kg) | 3.36 (2.84–3.88) | 3.38 (2.87–3.91) | 3.36 (2.84–3.89) | – |
| Female sex, n (%) | 143 (48) | 28 (64) | 115 (45) | – |
| Reason for paediatric attendance, n (%) | – | |||
| Preterm, 35+0–36+6 weeks gestation | 24 (8) | 5 (11) | 19 (7.5) | |
| Fetal growth restriction | 15 (5) | 3 (7) | 12 (5) | |
| Meconium-stained amniotic fluid | 85 (29) | 14 (32) | 71 (28) | |
| Abnormal CTG | 159 (53) | 24 (55) | 135 (53) | |
| Instrumental birth | 113 (38) | 4 (9) | 109 (43) | |
| Breech/transverse lie | 45 (15) | 12 (24) | 33 (13) | |
| Unplanned caesarean section | 115 (39) | 30 (68) | 75 (30) | |
| Other | 9 (3) | 0 (0) | 9 (4) | |
| Time from birth to | ||||
| Cord clamping (s) | 128 (123–145) | 125 (123–128) | 130 (123–149) | 0.003 |
| First cry (s) | 10 (3–25) | 18 (6–32) | 10 (3–24) | – |
| Regular cries (s) | 22 (10–37) | 37 (17–48) | 20 (8–34) | – |
| Average heart rate 90–120 s after birth (bpm)* | 173 (157–186) | 156 (137–163) | 177 (161–188) | – |
| n=283 | n=43 | n=240 | ||
| Average heart rate 120–150 s after birth (bpm)* | 172 (157–184) | 156 (142–167) | 174 (162–185) | – |
| n=283 | n=42 | n=241 | ||
| Outcomes | ||||
| Respiratory support provided, n (%) | – | |||
| None | 254 (85) | – | 254 (100) | |
| Any PPV | 5 (2) | 5 (11) | – | |
| CPAP±oxygen | 33 (11) | 33 (75) | – | |
| Oxygen alone | 6 (2) | 6 (14) | – | |
| Time from birth to commence respiratory support (s) | 214 (156–326) | 214 (155–326) | – | – |
| Apgar score | ||||
| 1 min | 9 (8–9) | 8 (7–9) | 9 (8–9) | <0.001 |
| 5 min | 9 (9–9) | 9 (8–9) | 9 (9–9) | <0.001 |
| Admitted to the neonatal unit, n (%) | 35 (12) | 18 (41) | 17 (7) | <0.001 |
| Primary reason for admission, n (%) | ||||
| Respiratory support | 17 (6) | 14 (32) | 3 (1) | <0.001 |
| Prematurity or low birth weight alone | 6 (2) | 1 (2) | 5 (2) | |
| Low glucose | 5 (2) | 2 (5) | 3 (1) | – |
| Other | 7 (2) | 1 (2) | 6 (2) | – |
Continuous variables are shown as median (IQR) except for birth weight, which was normally distributed and is shown as mean (SD).
P values represent univariable comparisons between infants who received respiratory support vs infants who received no respiratory support for important study outcomes.
*At the heart rate data points at 90 s, 100 s, 110 s, 120 s, 130 s, 140 s and 150 s, there were 46, 41, 33, 26, 28, 32 and 38 missing values, respectively.
bpm, beats per minute; CPAP, continuous positive airway pressure; CTG, cardiotocography; PPV, positive pressure ventilation.