Clinical characteristics of the study group, and incidence of (severe) retinopathy of prematurity for each characteristic
| Characteristic | Study group (%) | Infants with ROP (%)* | Infants with severe ROP (%)* |
|---|---|---|---|
| No | 1380 | 302 (21.9) | 29 (2.1) |
| Median gestational age (weeks) (P25–P75) | 29.8 (28.1–31.1) | 28.0 (26.4–29.4) | 26.3 (25.4–27.0) |
| Median birth weight (g) (P25–P75) | 1260 (1020–1500) | 950 (780–1212) | 890 (730–1060) |
| Extremely low birth weight (<1000 g) | 345 (25.0) | 178 (51.6) | 6 (1.7) |
| Small for gestational age (<P10) | 106 (7.7) | 25 (23.6) | 1 (0.9) |
| Female gender | 527 (38.2) | 108 (20.5) | 13 (2.5) |
| AV | 529 (38.3) | 167 (31.6) | 20 (3.8) |
| Supplemental O2 administration | 694 (50.3) | 186 (26.8) | 22 (3.2) |
| NICU admission | 1048 (75.9) | 228 (21.8) | 21 (2.0) |
| BPD | 65 (4.7) | 38 (58.5) | 8 (12.3) |
| Sepsis | 404 (29.3) | 128 (31.7) | 15 (3.7) |
| IVH/PVH | 207 (15.0) | 64 (30.9) | 8 (3.9) |
| iNO | 23 (1.7) | 11 (47.8) | 2 (8.7) |
| Prenatal glucocorticoïds | 622 (45.1) | 122 (19.6) | 11 (1.8) |
| Postnatal glucocorticoïds | 78 (5.7) | 45 (57.7) | 14 (17.9) |
| IRDS | 663 (48.0) | 177 (26.7) | 20 (3.0) |
| NEC with perforation | 27 (2.0) | 17 (63.0) | 5 (18.5) |
| Erythrocyte transfusion | 549 (39.8) | 186 (33.9) | 20 (3.6) |
*Percentages: fraction of patients in this group with ROP or severe ROP, unless indicated otherwise.
AV, artificial ventilation; BPD, bronchopulmonary dysplasia (extra oxygen needed at 36 weeks of gestation); iNO, inhaled nitric oxide; IRDS, infant respiratory distress syndrome; IVH/PVH, intra- or periventricular haemorrhage; NEC, necrotising enterocolitis; NICU, neonatal intensive care unit; P, percentile; ROP, retinopathy of prematurity.