Neonatal characteristics of SPRING participants and of all VPT infants born in the participating/study sites and in England during the recruitment period (May 2017–June 2018)
| SPRING participants (n=848) | All eligible infants born in study sites (n=4491) | National cohort (n=8998) | |
| Gestational age in weeks, median (IQR) | 28.9 (26–30) | 29 (27–30) | 29 (27–30) |
| Birth weight in grams, median (IQR) | 1120 (886–1420) | 1175 (882–1480) | 1170 (880–1470) |
| Boys, n (%) | 456 (53.8) | 2469 (55.0) | 4900 (54.5) |
| Singleton pregnancy, n (%) | 638 (75.2) | 3359 (74.8) | 6706 (74.5) |
| Spontaneous onset of labour, n (%) | 474 (55.9) | 2431 (54.1) | 4815 (53.5) |
| Caesarean section delivery, n (%) | 498 (58.7) | 2584 (57.5) | 5087 (56.5) |
| Maternal age at birth in years, median (IQR) | 31 (27–35) | Information not available | Information not available |
SPRING, study of preterm infants and neurodevelopmental genes; VPT, very preterm.