Table 1 Characteristics of participants
Neonatal factors | Group | Boy | Girl | P | ||
|---|---|---|---|---|---|---|
Total, n | Total, n | |||||
Gestational age, mean (SD), wk | 22–24 wk | 88 | 24.0 (0.6) | 100 | 23.9 (0.6) | 0.284 |
25–27 wk | 213 | 26.5 (0.9) | 227 | 26.5 (0.9) | 0.889 | |
28–31 wk | 482 | 30.1 (1.2) | 468 | 30.1 (1.1) | 0.865 | |
Birth weight, mean (SD), g | 22–24 wk | 88 | 645 (86) | 100 | 597 (80) | † |
25–27 wk | 213 | 921 (120) | 227 | 861 (119) | † | |
28–31 wk | 482 | 1,408 (204) | 468 | 1,350 (200) | † | |
Birth length, mean (SD), cm | 22–24 wk | 88 | 30.0 (1.5) | 100 | 29.8 (1.5) | 0.421 |
25–27 wk | 213 | 34.0 (1.8) | 227 | 33.6 (1.5) | ** | |
28–31 wk | 482 | 39.3 (2.0) | 468 | 38.9 (2.0) | ** | |
Birth head circumference, mean (SD), cm | 22–24 wk | 87 | 22.0 (1.4) | 98 | 21.4 (1.5) | * |
25–27 wk | 211 | 24.5 (1.3) | 219 | 24.0 (1.1) | † | |
28–31 wk | 480 | 28.0 (1.5) | 465 | 27.5 (1.5) | † | |
Multiple births, n (%) | 22–24 wk | 88 | 21 (23.9%) | 100 | 18 (18.0%) | 0.369 |
25–27 wk | 213 | 35 (16.4%) | 227 | 39 (17.2%) | 0.899 | |
28–31 wk | 482 | 136 (28.2%) | 468 | 123 (26.3%) | 0.513 | |
Necrotizing enterocolitis, n (%) | 22–24 wk | 86 | 2 (2.3%) | 99 | 3 (3.0%) | ‡ |
25–27 wk | 209 | 6 (2.9%) | 225 | 2 (0.9%) | .162 | |
28–31 wk | 482 | 4 (0.8%) | 467 | 1 (0.2%) | .374 | |
Sepsis, n (%) | 22–24 wk | 86 | 11 (12.8%) | 99 | 13 (13.1%) | ‡ |
25–27 wk | 209 | 20 (9.6%) | 225 | 13 (5.8%) | 0.150 | |
28–31 wk | 481 | 10 (2.1%) | 467 | 12 (2.6%) | 0.670 | |
Periventricular leukomalacia, n (%) | 22–24 wk | 86 | 1 (1.2%) | 99 | 2 (2.0%) | ‡ |
25–27 wk | 209 | 2 (1.0%) | 225 | 4 (1.8%) | 0.687 | |
28–31 wk | 481 | 5 (1.0%) | 467 | 7 (1.5%) | 0.573 | |
Intraventricular hemorrhage ≥grade III/IV, n (%) | 22–24 wk | 86 | 2 (2.3%) | 99 | 5 (5.1%) | 0.452 |
25–27 wk | 209 | 6 (2.9%) | 225 | 5 (2.2%) | 0.765 | |
28–31 wk | 482 | 6 (1.2%) | 467 | 4 (0.9%) | 0.753 | |
Chronic lung disease, n (%) | 22–24 wk | 86 | 65 (75.6%) | 99 | 71 (71.7%) | 0.618 |
25–27 wk | 209 | 105 (50.2%) | 223 | 104 (46.6%) | 0.500 | |
28–31 wk | 481 | 48 (10.0%) | 467 | 31 (6.6%) | 0.077 | |
Home oxygen therapy, n (%) | 22–24 wk | 85 | 27 (31.8%) | 99 | 20 (20.2%) | 0.090 |
25–27 wk | 209 | 20 (9.6%) | 225 | 17 (7.6%) | 0.494 | |
28–31 wk | 480 | 12 (2.5%) | 467 | 11 (2.4%) | ‡ | |
Tracheotomy, n (%) | 22–24 wk | 85 | 1 (1.2%) | 99 | 2 (2.0%) | ‡ |
25–27 wk | 209 | 1 (0.5%) | 225 | 2 (0.9%) | ‡ | |
28–31 wk | 480 | 1 (0.2%) | 467 | 1 (0.2%) | ‡ | |
Home ventilation, n (%) | 22–24 wk | 85 | 0 (0.0%) | 99 | 2 (2.0%) | 0.500 |
25–27 wk | 209 | 0 (0.0%) | 223 | 0 (0.0%) | - | |
28–31 wk | 480 | 3 (0.6%) | 467 | 0 (0.0%) | 0.249 | |
Tube feeding at home, n (%) | 22–24 wk | 85 | 2 (2.4%) | 99 | 6 (6.1%) | 0.290 |
25–27 wk | 209 | 0 (0.0%) | 225 | 0 (0.0%) | - | |
28–31 wk | 480 | 1 (0.2%) | 467 | 0 (0.0%) | ‡ | |
Visual impairment, n (%) | 22–24 wk | 84 | 8 (9.5%) | 97 | 4 (4.1%) | 0.230 |
25–27 wk | 207 | 5 (2.4%) | 224 | 7 (3.1%) | 0.773 | |
28–31 wk | 470 | 1 (0.2%) | 463 | 0 (0.0%) | ‡ | |
Hearing impairment, n (%) | 22–24 wk | 84 | 1 (1.2%) | 97 | 1 (1.0%) | ‡ |
25–27 wk | 208 | 4 (1.9%) | 224 | 2 (0.9%) | 0.434 | |
28–31 wk | 476 | 0 (0.0%) | 466 | 1 (0.2%) | 0.495 |
