Table 1.
Demographics of extremely preterm (EP) infants and the mothers in outcome categories
| Characteristics | Survivors (N = 1076) | Non-survivors (N = 975) | Total (N = 2051) | p-value | OR (95% CI) |
|---|---|---|---|---|---|
| Characteristics of infants | |||||
| GA (weeks), mean ± SD | 26.92 ± 0.86 | 26.41 ± 1.07 | 26.68 ± 1.00 | <0.001 | / |
| BW (grams), mean ± SD | 976 ± 167 | 889 ± 180 | 935 ± 179 | <0.001 | / |
| Gender (male), n (%) | 669 (62.2) | 586 (60.1) | 1255 (61.2) | >0.05 | 1.091 (0.913–1.303) |
| Apgar score, n (%) | |||||
| ≤ 3 at 1 min | 95 (8.8) | 168 (17.2) | 263 (12.8) | <0.001 | 0.465 (0.356–0.608) |
| 4~7 at 1 min | 369 (34.3) | 391 (40.1) | 760 (37.1) | <0.01 | 0.780 (0.651–0.933) |
| ≤ 3 at 5 min | 9 (0.8) | 43 (4.4) | 52 (2.5) | <0.001 | 0.183 (0.089–0.377) |
| 4~7 at 5 min | 130 (12.1) | 214 (21.9) | 344 (16.8) | <0.001 | 0.489 (0.385–0.620) |
| Surfactant therapy, n (%) | 900 (83.6) | 718 (73.6) | 1618 (78.9) | <0.001 | 1.830 (1.476–2.270) |
| Surfactant therapy twice or more, n (%) | 155 (14.4) | 155 (15.9) | 310 (15.1) | >0.05 | 0.890 (0.699–1.134) |
| Mechanical ventilation, n (%) | 816 (75.8) | 787 (80.7) | 1603 (78.2) | <0.01 | 0.750 (0.607–0.926) |
| Days of mechanical ventilation (days), median (P25, P75) | 8.0 (2.0,22.0) | 2.3 (1.0,7.3) | 4.2 (1.0,15.0) | <0.001 | / |
| Non-invasive ventilation, n (%) | 880 (81.8) | 240 (24.6) | 1120 (54.6) | <0.001 | 13.750 (11.117–17.007) |
| Days of non-invasive ventilation (days), median (P25, P75) | 15.4 (6.0,26.0) | 3.1 (1.0,8.0) | 12.0 (4.0,23.0) | <0.001 | / |
| Total days of oxygen therapy (days), median (P25, P75) | 42.7 (25.0,60.6) | 3.0 (1.0,9.8) | 19.5 (2.8,47.0) | <0.001 | / |
| Length of hospital stay (days), median (P25, P75) | 71.0 (55.5,87.0) | 3.0 (1.0,10.0) | 35.0 (3.0,73.0) | <0.001 | / |
| Characteristics of mothers | |||||
| History of pregnancy problemsa, n (%) | 412 (38.3) | 349 (35.8) | 761 (37.1) | >0.05 | 1.113 (0.930–1.332) |
| Age ≥ 35 years, n (%) | 238 (22.1) | 177 (18.2) | 415 (20.2) | <0.05 | 1.280 (1.030–1.591) |
| Cesarean section, n (%) | 221 (20.5) | 172 (17.6) | 393 (19.2) | >0.05 | 1.207 (0.967–1.506) |
| Twin/multiple pregnancy, n (%) | 392 (36.4) | 404 (41.4) | 796 (38.8) | <0.05 | 0.810 (0.678–0.968) |
| Antenatal steroids, n (%) | 609 (56.6) | 367 (37.6) | 976 (47.6) | <0.001 | 2.160 (1.810–2.579) |
| Dexamethasone ≥ 4 doses | 390 (36.2) | 204 (20.9) | 594 (29.0) | <0.001 | 2.149 (1.762–2.620) |
| Dexamethasone 1~3 dose(s) | 219 (20.4) | 163 (16.7) | 382 (18.6) | <0.05 | 1.273 (1.017–1.593) |
| Premature rupture of membranes, n (%) | 305 (28.3) | 194 (19.9) | 499 (24.3) | <0.001 | 1.593 (1.297–1.956) |
| Infection in the middle trimester of pregnancy, n (%) | 82 (7.6) | 66 (6.8) | 148 (7.2) | >0.05 | 1.136 (0.812–1.590) |
| Gestational diabetes mellitus, n (%) | 99 (9.2) | 88 (9.0) | 187 (9.1) | >0.05 | 1.021 (0.756–1.380) |
| Pregnancy induced hypertension syndrome, n (%) | 71 (6.6) | 80 (8.2) | 151 (7.4) | >0.05 | 0.790 (0.567–1.102) |
| Placental abruption/Placenta previa, n (%) | 72 (6.7) | 81 (8.3) | 153 (7.5) | >0.05 | 0.792 (0.569–1.101) |
| Thyroid dysfunction, n (%) | 31 (2.9) | 22 (2.3) | 53 (2.6) | >0.05 | 1.285 (0.739–2.235) |
| Cervical incompetence, n (%) | 28 (2.6) | 48 (4.9) | 76 (3.7) | <0.01 | 0.516 (0.321–0.829) |
P-value means the contrast between survivors and non-survivors
GA gestational age, BW birth weight, SD standard deviation, P25 the 25th percentile, P75 the 75th percentile, OR odds ratio, CI confidence interval
aHistory of pregnancy problems refer to that the mother had at least one of the histories as follow: spontaneous abortion, induced abortion, stillbirth, preterm birth, ectopic pregnancy, or baby died during the neonatal period