Patient characteristics
| Chronic lung disease | Resolved respiratory distress syndrome | Term control | |
| Number of patients | 20 | 17 | 6 |
| Number of samples | 130 | 45 | 23 |
| Gestational age (weeks) | 27 (25+4–29+3)* | 28 +6 (27–29+2)* | Term |
| Birth weight (g) | 835 (695–1025) | 1120 (935–1315) | 2550 (2090–2825) |
| M:F | 11:9 | 10:7 | 3:3 |
| Vaginal:caesarean delivery | 10:10 | 6:11 | 5:1 |
| Antenatal steroids >24 h | 16/20 (80%) | 12/17 (71%) | 0/6 (0%) |
| Surfactant therapy | 20/20 (100%) | 17/17 (100%) | 0/6 (0%) |
| Prolonged rupture of membranes (>24 h) | 4/20 (20%) | 1/17 (6%) | 0/6 |
| Length of ventilation (days) | 7 (5.5–11) | 1 (1–4.5) | 3 |
↵* Values are shown as median (IQR).
Superscript numbers indicate the number of days in addition to gestation in weeks.