Comparison of baseline and neonatal characteristics of infants with and without BPD
| All infants n=610 n (%) Mean (SD) | No BPD n=253 n (%) Mean (SD) | BPD n=357 n (%) Mean (SD) | P value* | |
| Outborn | 50 (8%) | 27 (11%) | 23 (6%) | 0.061 |
| Male gender | 307 (50%) | 113 (45%) | 194 (54%) | 0.013 |
| Gestational age (weeks) | 27.9 (1.37) | 28.5 (1.13) | 27.4 (1.32) | <0.001 |
| Birth weight (gram) | 1030 (250) | 1.130 (242) | 965 (226) | <0.001 |
| z-score | 0.27 (0.85) | 0.43 (0.80) | −0.13 (0.85) | 0.015 |
| Small for gestational age† | 53 (9%) | 21 (8%) | 32 (9%) | 0.753 |
| Singleton | 168 (27%) | 64 (26%) | 104 (30%) | 0.269 |
| Antenatal corticosteroids (completed) | 442 (72%) | 181 (71%) | 261 (73%) | 0.669 |
| Chorioamnionitis | 143 (23%) | 59 (25%) | 84 (24%) | 0.866 |
| Caesarean delivery | 507 (83%) | 205 (81%) | 302 (84%) | 0.247 |
| Umbilical artery pH | 7.31 (0.09) | 7.31 (0.08) | 7.31 (0.09) | 0.874 |
| Days of mechanical ventilation | 3.4 (6.2) | 1.3 (3.3) | 3.5 (7.2) | 0.001 |
| Surfactant | 267 (44%) | 76 (30%) | 191 (53%) | <0.001 |
| Intraventricular haemorrhage >grade 2 | 44 (7%) | 10 (4%) | 34 (9%) | 0.009 |
| Cystic periventricular leukomalacia | 6 (1%) | 4 (2%) | 2 (1%) | 0.206 |
| Retinopathy of prematurity >grade 2 | 10 (2%) | 6 (2%) | 14 (4%) | 0.315 |
| Sepsis | 115 (19%) | 25 (10%) | 90 (25%) | <0.001 |
| Necrotising enterocolitis | 22 (4%) | 10 (4%) | 12 (3%) | 0.700 |
| Persistent ductus arteriosus | 319 (52%) | 99 (39%) | 220 (62%) | <0.001 |
| Socioeconomic score | 5.9 (2.5) | 5.9 (2.5) | 5.8 (2.5) | 0.921 |
*Comparison between infants with and without BPD: Pearson’s χ2 (or Fisher exact) test (for dichotomous variables) and independent t-test and Mann-Whitney U tests (for linear variables).
†Birth weight <10th percentile.
BPD, bronchopulmonary dysplasia.