Postnatal (PNA) and postmenstrual age (PMA) at detection of retinopathy of prematurity (ROP), ROP stage 3 and first treatment, time from detected ROP to treatment and number of examinations in relation to gestational age (GA)
| GA (weeks) | 21/22 † | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | Total |
| Detection first ROP PNA (weeks)* | 10.9 (7.9:23.1) | 10.1 (6.3:22.0) | 9.6 (6.1:27.0) | 9.0 (6.1:16.3) | 8.4 (4.9:17.6) | 8.1 (4.9:15.3) | 7.9 (4.1:15.0) | 7.4 (4.7:11.9) | 7.0 (4.7:11.4) | 9.0 (4.1:27) |
| PMA (weeks)* | 33.4 (30.4:46.0) | 33.7 (29.4:45.1) | 34.0 (31.0:51.3) | 34.4 (31.6:41.4) | 34.9 (31.6:44.0) | 35.4 (32.3:42.4) | 36.3 (32.9:43.3) | 36.7 (33.7:41.4) | 37.7 (34.9:42.1) | 34.9 (29.4:51.3) |
| N | 68 | 207 | 314 | 353 | 363 | 226 | 170 | 101 | 53 | 1855 |
| Detection ROP3 PNA (weeks)* | 11.9 (9.6:23.1) | 12.0 (8.4:25.6) | 11.7 (7.3:23.9) | 11.7 (7.0:27.7) | 11.7 (7.0:26.1) | 12.4 (4.9:22.7) | 10.8 (6.4:17.9) | 10.6 (6.6:18.4) | 8.6 (5.0:10.9) | 11.9 (4.9:27.7) |
| PMA (weeks)* | 34.6 (32.3:46.0) | 35.5 (31.7:48.7) | 36.1 (31.7:48.4) | 37.0 (32.7:53.0) | 38.1 (33.7:52.9) | 39.7 (32.3:49.9) | 39.0 (34.4:46.3) | 40.1 (36.0:48.3) | 39.0 (35.1:41.4) | 36.7 (31.7:53) |
| N | 53 | 140 | 176 | 147 | 121 | 44 | 28 | 15 | 10 | 734 |
| First treatment PNA (weeks)* | 12.4 (9.7:24.3) | 12.6 (9.4:28.3) | 12.3 (8.3:21.4) | 12.6 (7.4:21.9) | 12.8 (7.0:25.9) | 12.8 (8.7:17.7) | 11.6 (7.6:18.9) | 11.1 (8.0:17.4) | NA (Inf:-Inf) | 12.4 (7:28.3) |
| PMA (weeks)* | 35.1 (32.1:47.1) | 35.9 (32.9:51.4) | 36.6 (32.4:45.7) | 37.9 (33.1:47.0) | 39.2 (33.1:52.1) | 40.2 (35.7:45.3) | 39.6 (36.1:47.7) | 40.7 (37.6:46.6) | NA (Inf:-Inf) | 36.9 (32.1:52.1) |
| N | 43 | 109 | 120 | 83 | 58 | 14 | 9 | 4 | 0 | 440 |
| Days from first ROP to treatment* | 18.0 (3:95) | 17.0 (2:87) | 20.0 (1:77) | 28.0 (2:86) | 24.5 (3:133) | 30.0 (15:78) | 12.0 (2:79) | 22.0 (5:71) | NA (Inf:-Inf) | 22.0 (1:133) |
| Number of examinations* | 14.0 (3:42) | 14.0 (1:39) | 12.0 (2:40) | 10.0 (2:37) | 7.0 (2:35) | 5.0 (1:27) | 4.0 (1:29) | 4.0 (1:24) | 3.0 (1:21) | 4.0 (1:42) |
| Total number of examinations | 1333 | 3722 | 5527 | 6407 | 6729 | 5672 | 5726 | 5690 | 5232 | 46 038 |
*Median and ranges are given.
†There were two infants born at 21 w, both developed ROP stage 3 and were treated for ROP.