Survival by population characteristics for infants born 22+0–31+6 weeks’ gestation, England 2008–2014, and admitted to a neonatal unit contributing to the National Neonatal Research Database
| Survived to discharge | Missing | p Value | Survived to 28 days | Missing | p Value | ||||
| n | % (95% CI) | n | % (95% CI) | ||||||
| Gestational (age weeks +days ) | 22+0–22+6 | 12 | 17.9 (8.7 to 27.2) | 1 | 17 | 25.4 (14.9 to 35.9) | 1 | ||
| 23+0–23+6 | 440 | 35.9 (33.2 to 38.6) | 56 | 629 | 49.6 (46.8 to 52.3) | 12 | |||
| 24+0–24+6 | 1464 | 58.6 (56.6 to 60.5) | 144 | 1819 | 69.6 (67.8 to 71.4) | 31 | |||
| 25+0–25+6 | 2091 | 74 (72.4 to 75.6) | 167 | 2421 | 81.7 (80.3 to 83) | 28 | |||
| 26+0–26+6 | 3199 | 83.4 (82.3 to 84.6) | 184 | p<0.001 | 3517 | 88.2 (87.2 to 89.2) | 30 | p<0.001 | |
| 27+0–27+6 | 4125 | 88.4 (87.5 to 89.4) | 208 | 4426 | 91.9 (91.2 to 92.7) | 57 | |||
| 28+0–28+6 | 5556 | 92.4 (91.7 to 93) | 231 | 5839 | 94.5 (93.9 to 95.1) | 68 | |||
| 29+0–29+6 | 6599 | 95.7 (95.3 to 96.2) | 212 | 6770 | 96.6 (96.2 to 97) | 95 | |||
| 30+0–30+6 | 8491 | 97.5 (97.1 to 97.8) | 232 | 8621 | 97.8 (97.5 to 98.1) | 128 | |||
| 31+0–31+6 | 11 467 | 98.1 (97.9 to 98.4) | 255 | 11 603 | 98.4 (98.2 to 98.7) | 153 | |||
| Birth weight (g) | <500 | 127 | 34.8 (29.9 to 39.7) | 17 | 192 | 50.7 (45.6 to 55.7) | 3 | ||
| 500–999 | 11 748 | 76.8 (76.2 to 77.5) | 772 | 13 256 | 83.4 (82.8 to 84) | 167 | |||
| 1000–1499 | 19 918 | 95.6 (95.3 to 95.9) | 613 | p<0.001 | 20 431 | 96.4 (96.1 to 96.6) | 259 | p<0.001 | |
| 1500–1999 | 10 913 | 97.9 (97.7 to 98.2) | 262 | 11 031 | 98.1 (97.8 to 98.3) | 158 | |||
| ≥2000 | 738 | 94.4 (92.8 to 96) | 26 | 752 | 94.9 (93.4 to 96.5) | 16 | |||
| Small-for-gestational age | No | 37 309 | 90.4 (90.1 to 90.7) | 1406 | p<0.001 | 38 985 | 92.5 (92.2 to 92.7) | 538 | p<0.001 |
| Yes | 6135 | 85.9 (85.1 to 86.7) | 284 | 6677 | 90.7 (90.1 to 91.4) | 65 | |||
| Sex | Girls | 20 190 | 90.6 (90.2 to 91) | 732 | p<0.001 | 21 090 | 92.8 (92.5 to 93.1) | 284 | p<0.001 |
| Boys | 23 254 | 88.9 (88.6 to 89.3) | 958 | 24 572 | 91.7 (91.4 to 92.1) | 319 | |||
| Multiplicity of pregnancy | Singleton | 31 845 | 89.7 (89.4 to 90.1) | 1225 | p<0.001 | 33 506 | 92.3 (92 to 92.6) | 417 | p<0.001 |
| Twins | 10 472 | 89.3 (88.7 to 89.9) | 433 | 10 992 | 91.7 (91.2 to 92.2) | 172 | |||
| Triplets+ | 1127 | 93.1 (91.7 to 94.6) | 32 | 1164 | 94.8 (93.5 to 96) | 14 | |||
| Any antenatal steroids given | No | 4421 | 82.1 (81.1 to 83.2) | 233 | p<0.001 | 4711 | 85 (84 to 85.9) | 72 | p<0.001 |
| Yes | 38 327 | 90.8 (90.5 to 91) | 1369 | 40 196 | 93.2 (93 to 93.5) | 485 | |||
| Mode of delivery | Vaginal | 16 346 | 85.9 (85.4 to 86.4) | 546 | p<0.001 | 17 275 | 82.1 (81.1 to 83.2) | 190 | p<0.001 |
| Caesarean | 23 473 | 93 (92.7 to 93.3) | 665 | 24 367 | 90.8 (90.5 to 91) | 227 | |||
| Maternal age | <20 | 3143 | 88.3 (87.2 to 89.3) | 147 | p<0.001 | 3326 | 90.9 (90 to 91.9) | 51 | p<0.001 |
| 20–24 | 7639 | 88.5 (87.8 to 89.1) | 308 | 8063 | 91.3 (90.7 to 91.9) | 108 | |||
| 25–29 | 11 268 | 90.3 (89.7 to 90.8) | 395 | 11 821 | 92.7 (92.2 to 93.1) | 122 | |||
| 30–34 | 11 890 | 90 (89.5 to 90.5) | 421 | 12 460 | 92.5 (92.1 to 92.9) | 157 | |||
| 35–40 | 7171 | 90.4 (89.7 to 91) | 246 | 7505 | 92.8 (92.2 to 93.3) | 89 | |||
| >40 | 2105 | 90.7 (89.6 to 91.9) | 67 | 2198 | 93 (91.9 to 94) | 23 | |||
Percentages exclude missing. p Value from Χ2 tests.