Baseline characteristics and first transfer details by place of birth
| Place of birth | Neonatal surgical unit, n=660 | Tertiary designated unit, n=337 | Tertiary non-designated unit, n=89 | Non-tertiary unit, n=233 |
| Infant characteristics at birth | ||||
| <28 weeks’ gestation, n (%) | 5 (1) | 2 (1) | 2 (2) | 1 (<1) |
| ≥28 to 32 weeks’ gestation, n (%) | 30 (4) | 5 (1) | 5 (6) | 20 (9) |
| ≥32 to 36+6 weeks’ gestation, n (%) | 132 (20) | 63 (19) | 20 (22) | 46 (20) |
| >37 weeks’ gestation, n (%) | 493 (75) | 267 (79) | 62 (70) | 166 (71) |
| Gestation in weeks, median (IQR) | 38 (36, 39) | 38 (37, 39) | 38 (35, 40) | 38 (36, 40) |
| Girls, n (%) | 279 (42) | 136 (40) | 38 (43) | 83 (36) |
| Multiple birth, n (%) | 34 (5) | 16 (5) | 5 (6) | 8 (4) |
| Birth weight (g), median (IQR) | 2897 (2444, 3250) | 3000 (2575, 3370) | 2960 (2280, 3442) | 3080 (2420, 3470) |
| Caesarean delivery, n (%) | 241 (38) | 120 (36) | 36 (40) | 82 (35) |
| Missing, n (%) | 46 (7) | 9 (3) | 5 (6) | 3 (1) |
| Maternal characteristics | ||||
| Maternal age, median (IQR) | 31.0 (27.0, 35.0) | 30.0 (26.0, 34.0) | 30.0 (26.0, 34.0) | 31.0 (27.0, 35.0) |
| Missing, n (%) | 4 (<1) | 4 (2) | 2 (2) | 0 (0) |
| Index of Multiple Deprivation decile, median (IQR) | 5.00 (2.00, 7.00) | 3.50 (2.00, 6.00) | 3.00 (2.00, 6.00) | 5.00 (3.00, 8.00) |
| Missing, n (%) | 12 (2) | 7 (2) | 0 (0) | 4 (2) |
| Maternal ethnicity | ||||
| White British, n (%) | 337 (51) | 183 (54) | 52 (58) | 116 (50) |
| Missing, n (%) | 95 (14) | 71 (21) | 10 (11) | 46 (20) |
| Maternal gestational diabetes, n (%) | 41 (6) | 21 (6) | 4 (5) | 15 (6) |
| Smoking in pregnancy, n (%) | 78 (12) | 46 (14) | 15 (17) | 30 (13) |
| Missing, n (%) | 97 (15) | 35 (10) | 8 (9) | 25 (11) |
| Received antenatal care, n (%) | 486 (74) | 225 (67) | 68 (76) | 162 (68) |
| Missing, n (%) | 113 (17) | 78 (20) | 12 (13) | 58 (24) |
| Apgar score >7 at 5 min, n (%) | 358 (54) | 185 (55) | 50 (56) | 130 (55) |
| Organisational factors | ||||
| Admission to neonatal unit <2 hours from birth, n (%) | 627 (95) | 330 (98) | 69 (78) | 175 (74) |
| Median time admission from birth, min (IQR) | 25 (17–35) | 18 (14–25) | 34 (24–82) | 43 (25–125) |
| Transfer to another hospital at <24 hours from birth, n (%) | 16 (2) | 32 (10) | 53 (60) | 191 (81) |
| Transfer to another hospital at 24–48 hours from birth, n (%) | 22 (3) | 40 (12) | 9 (10) | 13 (6) |
| Transfer to another hospital at 48–72 hours from birth, n (%) | 3 (0.5) | 41 (12) | 6 (7) | 6 (3) |
| Median age transfer to surgical unit, days | N/A | 4 (1.8–4) | 1 (0.3–1.6) | 0.5 (0.3–0.6) |
| Transferred to a children’s hospital—including stand-alone surgical units, n (%) | 61 (9) | 241 (72) | 27 (30) | 67 (29) |
| Received all care in neonatal unit | 499 (76) | 121 (36) | 52 (58) | 163 (70) |
| Intervention on day 1 | ||||
| Received drugs at birth, n (%) | 133 (20) | 34 (10) | 4 (4.5) | 2 (0.8) |
| Received inotropes on day 1, n (%) | 332 (50) | 169 (50) | 27 (30) | 61 (26) |
| Received nitric oxide on day 1, n (%) | 287 (43) | 149 (44) | 22 (25) | 25 (11) |
| Received mechanical ventilation on day 1, n (%) | 601 (91) | 309 (92) | 66 (74) | 148 (64) |
| ECMO use during neonatal stay | ||||
| Received ECMO or discharge from unit for ECMO, n (%) | 54 (8) | 28 (8) | 8 (9) | 8 (3) |
| Median age ECMO transfer, days (IQR) | 1.3 (0.9–2.1) | 1.1 (0.6–1.8) | 1 (0.5–4.3) | 1.5 (0.8–1.8) |
| Ventilation mode during NNU stay | ||||
| Conventional ventilation only, n (%) | 216 (45) | 49 (24)* | 53 (70)* | 160 (80)* |
| High-frequency oscillation only, n (%) | 73 (15) | 39 (19)* | 2 (2.6)* | 4 (2.0)* |
| Multiple modes of ventilation, n (%) | 195 (40) | 114 (53)* | 21 (28)* | 37 (18)* |
| Unknown, n (%) | 15 (3) | 12 (5)* | 4 (5) | 15 (7)* |
| Surfactant administration outside of delivery room | ||||
| Surfactant given, yes, n (%) | 70 (14) | 38 (18)* | 25 (31)* | 54 (25)* |
| Sildenafil use during NNU stay | ||||
| Sildenafil given, yes, n (%) | 24 (5) | 14 (6.5)* | 4 (5.0)* | 10 (4.6)* |
| Inhaled nitric oxide during NNU stay | ||||
| Inhaled nitric oxide given, yes, n (%) | 283 (57) | 140 (66)* | 33 (41)* | 67 (31)* |
| Prostaglandin use during NNU stay | ||||
| Prostaglandin given, yes, n (%) | 41 (8) | 44 (21)* | 8 (10)* | 14 (6.5)* |
*Reported for 1170 infants. Tertiary designated n=214, tertiary non-designated n=80, non-tertiary unit n=216.
ECMO, extracorporeal membrane oxygenation; NNU, neonatal unit.