Incidence of retinopathy of prematurity (ROP) and frequency of treatment in relation to gestational age (GA)
| GA (weeks) | 21/22* n=87 | 23 n=260 | 24 n=429 | 25 n=589 | 26 n=774 | 27 n=891 | 28 n=1134 | 29 n=1404 | 30 n=1681 | Total n=7249 |
| ROP stage, n (%) | ||||||||||
| 0 | 9 (10.3) | 26 (10.0) | 72 (16.8) | 155 (26.3) | 349 (45.1) | 606 (68.0) | 907 (80.0) | 1225 (87.3) | 1590 (94.6) | 4939 (68.1) |
| 1 | 5 (5.7) | 26 (10.0) | 54 (12.6) | 93 (15.8) | 105 (13.6) | 118 (13.2) | 116 (10.2) | 95 (6.8) | 58 (3.5) | 670 (9.2) |
| 2 | 16 (18.4) | 57 (21.9) | 109 (25.4) | 178 (30.2) | 184 (23.8) | 118 (13.2) | 79 (7.0) | 66 (4.7) | 23 (1.4) | 830 (11.4) |
| 3 | 54 (62.1) | 143 (55.0) | 183 (42.7) | 158 (26.8) | 135 (17.4) | 48 (5.4) | 32 (2.8) | 17 (1.2) | 10 (0.6) | 780 (10.8) |
| 4 | 1 (1.1) | 1 (0.4) | 4 (0.9) | 1 (0.2) | 0 (0.0) | 1 (0.1) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 8 (0.1) |
| 5 | 2 (2.3) | 7 (2.7) | 7 (1.6) | 4 (0.7) | 1 (0.1) | 0 (0.0) | 0 (0.0) | 1 (0.1) | 0 (0.0) | 22 (0.3) |
| Treated ROP,n (%) | 43 (49.4) | 109 (41.9) | 120 (28.0) | 83 (14.1) | 58 (7.5) | 14 (1.6) | 9 (0.8) | 4 (0.3) | 0 (0.0) | 440 (6.1) |
* There were two infants born at 21 weeks, both developed ROP stage 3 and were treated for ROP.