Associations between infant and pregnancy characteristics and severe morbidity: infants discharged from neonatal hospitalisation (n=6422)
| Characteristics | n | % | P | Adjusted RR (95% CI) |
| Infant characteristics | ||||
| Gestational age | ||||
| 23 | 19 | 61.3 | <0.001 | 45.55 (32.02 to 64.80) |
| 24 | 103 | 51.8 | 22.26 (14.51 to 34.15) | |
| 25 | 99 | 34.5 | 19.33 (13.91 to 26.86) | |
| 26 | 104 | 23.4 | 13.65 (9.75 to 19.11) | |
| 27 | 90 | 15.3 | 8.70 (6.19 to 12.24) | |
| 28 | 77 | 10.0 | 5.55 (3.91 to 7.89) | |
| 29 | 58 | 6.4 | 3.82 (2.66 to 5.49) | |
| 30 | 69 | 5.3 | 2.30 (1.56 to3.40) | |
| 31 | 44 | 2.6 | Ref | |
| Sex | ||||
| Male | 296 | 10.3 | 0.365 | Ref |
| Female | 367 | 11.0 | 1.10 (0.96 to 1.27) | |
| Type of pregnancy | ||||
| Singleton | 483 | 11.3 | 0.012 | Ref |
| Multiple | 180 | 9.2 | 0.94 (0.79 to 1.12) | |
| SGA* | ||||
| <10th | 183 | 9.1 | 0.008 | 0.82 (0.68 to 0.98) |
| ≥10th | 480 | 11.4 | Ref | |
| Maternal and pregnancy characteristics | ||||
| Maternal age | ||||
| <35 years | 497 | 10.9 | 0.200 | Ref |
| 35 years | 161 | 9.8 | 1.01 (0.86 to 1.18) | |
| Parity | ||||
| Nulliparous | 381 | 10.8 | 0.459 | Ref |
| Multiparous | 274 | 10.3 | 0.94 (0.81 to1.08) | |
| PPROM | 164 | 10.8 | 0.815 | 0.92 (0.78 to1.08) |
| Pre-eclampsia/ eclampsia/HELLP | 70 | 7.2 | <0.001 | 0.76 (0.59 to 0.98) |
| Congenital anomaly† | 67 | 14.5 | 0.005 | 1.34 (1.07 to 1.67) |
*Small for gestational age, using intrauterine references.
†Congenital anomalies reportable to Eurocat, but not severe. Cases with severe anomalies were excluded.
HELLP, hemolysis elevated liver enzymes low platelet count; PPROM, preterm premature rupture of membrane; RR, relative risk.