Table 2. Characteristic of infants without ROP and with any ROP.
| No ROP (n=3898) | Any ROP (n=242) | P value | |
|---|---|---|---|
| Infant and maternal characteristics | |||
| Gestational age (weeks), mean±SD, | 34±1 | 33±2 | <0.001 |
| <32 weeks, n (%) | 566 (14.4) | 66 (27.3) | <0.001 |
| 330/7–366/7 weeks, n (%) | 3332 (85.5) | 176 (72.2) | |
| Birth weight (g), mean±SD, | 2154±463 | 1900±447 | <0.001 |
| <1500 g, n (%) | 150 (3.8) | 26 (10.7) | <0.001 |
| 1500–1999 g, n (%) | 1472 (37.8) | 106 (43.8) | |
| >2000 g, n (%) | 2276 (58.4) | 110 (45.5) | |
| Maternal age (years), mean±SD | 30±6 | 30±6 | 0.314 |
| In vitro fertilisation, n (%) | 448 (11.5) | 28 (11.6) | 0.971 |
| Multiple births, n (%) | 1009 (25.9) | 61 (25.2) | 0.441 |
| Antenatal steroid, two doses, n (%) | 1186 (33.7) | 60 (29.6) | 0.024 |
| Chorioamnionitis, n (%) | 70 (1.8) | 2 (0.8) | 0.263 |
| Oligohydramnios, n (%) | 268 (6.9) | 21 (8.7) | 0.286 |
| Pre-eclampsia, n (%) | 530 (14.2) | 30 (13.1) | 0.653 |
| Gestational diabetes, n (%) | 373 (10.2) | 21 (9.4) | 0.679 |
| Small for gestational age, n (%) | 285 (7.3) | 28 (11.6) | 0.047 |
| Male gender, n (%) | 2088 (53.6) | 135 (55.8) | 0.502 |
| Caesarean section, n (%) | 3370 (86.5) | 209 (86.4) | 0.968 |
| Resuscitation at birth, n (%) | 1141 (29.3) | 113 (46.7) | <0.001 |
| Any RBC transfusion, n (%) | 306 (7.9) | 61 (25.2) | <0.001 |
| Delayed time to regain birth weight, n (%) | 710 (18.2) | 70 (28.9) | <0.001 |
| Early morbidities** | |||
| Respiratory distress syndrome, n (%) | 1104 (28.3) | 119 (49.2) | <0.001 |
| Patent ductus arteriosus treatment, n (%) | 139 (3.6) | 24 (9.9) | <0.001 |
| Intracranial haemorrhage (>grade II), n (%) | 194 (5.0) | 34 (14.0) | <0.001 |
| Early neonatal sepsis, n (%) | 843 (21.6) | 102 (42.1) | <0.001 |
| Culture-proven sepsis, n (%) | 42 (1.1) | 4 (1.7) | <0.001 |
| Late neonatal sepsis, n (%) | 538 (13.8) | 63 (26.0) | <0.001 |
| Culture-proven sepsis, n (%) | 172 (4.4) | 28 (11.6) | <0.001 |
| Necrotising enterocolitis (≥stage II), n (%) | 44 (1.1) | 12 (5.0) | <0.001 |
| Respiratory treatment characteristics | |||
| Initial respiratory support | <0.001 | ||
| None/oxygen, n (%) | 928 (23.8) | 21 (8.7) | |
| Non-invasive ventilation, n (%) | 1795 (46.0) | 89 (36.8) | |
| Mechanical ventilation, n (%) | 1175 (30.2) | 132 (54.5) | |
| Duration of oxygen;* (days), median (25p–75p) | 5 (1–9) | 10 (4–19) | <0.001† |
| Duration of positive pressure;* ‡ (days), median (25p–75p) | 4 (1–6) | 6 (3–11) | <0.001† |
| Duration of mechanical ventilation;* (days), median (25p–75p) | 0 (0–1) | 1 (0–6) | <0.001† |
| Any positive pressure on day 28, n (%) | 77 (2) | 12 (5.0) | 0.002 |
| Any oxygen treatment on day 28, n (%) | 168 (4.3) | 32 (13.2) | <0.001 |
| FiO2 on day 28, all infants | 21 (21–21) | 21 (21–21) | 0.164† |
The values are presented as mean±SD, median (25p–75p) and n (%) where appropriate.
*
All infants, until first examination.
†
Mann-Whitney U test.
‡
The last postnatal day on which the infant received any positive pressure support, either via mechanical or non-invasive ventilation.
FiO2, fractional inspired oxygen; RBC, red blood cell; ROP, retinopathy of prematurity.