Table 1.
Infant characteristics, growth and morbidity by gestational age at birth
| Gestational age at birth (weeks) |
||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 23 |
24 |
25 |
26 |
27 |
28 |
29 |
30 |
All |
||||||||||
| n | Per cent | n | Per cent | n | Per cent | n | Per cent | n | Per cent | n | Per cent | n | Per cent | n | Per cent | N | Per cent | |
| Infants | 117 | 4.6 | 314 | 12.5 | 399 | 15.8 | 482 | 19.1 | 249 | 9.9 | 296 | 11.7 | 323 | 12.8 | 341 | 13.5 | 2521 | 100 |
| Female sex | 58 | 49.6 | 137 | 43.6 | 190 | 47.6 | 229 | 47.5 | 119 | 47.8 | 139 | 47.0 | 134 | 41.5 | 162 | 47.5 | 1168 | 46.3 |
| Country | ||||||||||||||||||
| NA* | 53 | 45.3 | 168 | 53.5 | 190 | 47.6 | 227 | 47.1 | 237 | 95.2 | 277 | 93.6 | 299 | 92.6 | 319 | 93.5 | 1770 | 70.2 |
| Sweden | 64 | 54.7 | 146 | 46.5 | 209 | 52.4 | 255 | 52.9 | 12 | 4.8 | 19 | 6.4 | 24 | 7.4 | 22 | 6.4 | 751 | 29.8 |
| SGA | 5 | 4.3 | 38 | 12.1 | 81 | 20.3 | 115 | 23.9 | 77 | 30.9 | 110 | 37.2 | 107 | 33.1 | 114 | 33.4 | 647 | 25.7 |
| Mdn | IQR | Mdn | IQR | Mdn | IQR | Mdn | IQR | Mdn | IQR | Mdn | IQR | Mdn | IQR | Mdn | IQR | Mdn | IQR | |
| BW (g) | 595 | 550–655 | 675 | 610–735 | 770 | 693–858 | 890 | 776–995 | 989 | 865–1080 | 1071 | 921–1211 | 1287 | 1100–1420 | 1415 | 1195–1550 | 915 | 731–1153 |
| BWSDS (SDS) | −0.4 | −1.0–0.4 | −0.6 | −1.4–0.0 | −1.0 | −1.7–0.1 | −1.0 | −2.0–0.2 | −1.3 | −2.3–0.6 | −1.6 | −2.6–0.8 | −1.3 | −2.3–0.4 | −1.4 | −2.5–0.6 | −1.1 | −2.0–0.3 |
| Weight at 36 weeks PMA (g) | 2072 | 1847–2263 | 2123 | 1932–2319 | 2126 | 1881–2377 | 2190 | 1905–2415 | 2244 | 1922–2501 | 2179 | 1958–2500 | 2320 | 1973–2582 | 2206 | 1902–2506 | 2157 | 1909–2391 |
| WSDS at 36 weeks PMA (SDS) | −2.3 | −2.9–1.8 | −2.2 | −2.8–1.6 | −2.2 | −2.9–1.4 | −2.0 | −2.9–1.2 | −1.6 | −2.7–0.8 | −1.9 | −2.5–0.9 | −1.5 | −2.6–0.7 | −1.8 | −2.9–0.9 | −1.9 | −2.7–1.2 |
| Growth rate† (g/kg/d) | 13.7 | 12.6–15.2 | 13.8 | 12.6–15.2 | 13.8 | 12.7–15.4 | 13.8 | 12.3–15.4 | 13.7 | 12.3–15.2 | 13.3 | 11.6–14.9 | 12.4 | 11.0–14.2 | 11.8 | 9.8–13.9 | 13.3 | 11.8–15.0 |
| MAX rate (g/kg/d) | 18.9 | 11.5–23.6 | 18.3 | 12.2–23.8 | 19.7 | 13.1–25.6 | 20.3 | 13.4–25.6 | 21.7 | 17.8–25.1 | 20.5 | 16.9–23.8 | 20.4 | 16.6–23.7 | 19.0 | 15.7–22.7 | 17.7 | 11.3–22.7 |
| PMA @MAX | 30 | 30 | 30 | 30 | 31 | 32 | 33 | 34 | 31 | |||||||||
| n | Per cent | n | Per cent | n | Per cent | n | Per cent | n | Per cent | n | Per cent | n | Per cent | n | Per cent | N | Per cent | |
| ROP‡ | ||||||||||||||||||
| No | 9 | 7.7 | 17 | 5.4 | 69 | 17.3 | 166 | 34.4 | 99 | 39.8 | 185 | 62.5 | 236 | 73.1 | 304 | 89.1 | 1085 | 43.0 |
| ROP 1–2 | 40 | 34.2 | 131 | 41.9 | 215 | 54.0 | 236 | 49.0 | 127 | 51.0 | 98 | 33.1 | 84 | 26.0 | 34 | 10.0 | 965 | 38.3 |
| ROP≥3 | 68 | 58.1 | 165 | 52.7 | 114 | 28.6 | 80 | 16.6 | 23 | 9.2 | 13 | 4.4 | 3 | 0.9 | 3 | 0.9 | 471 | 18.7 |
| Trt | 51 | 43.6 | 109 | 34.9 | 65 | 16.3 | 39 | 8.1 | 16 | 6.4 | 5 | 1.7 | 3 | 0.9 | 0 | 0.0 | 288 | 11.4 |
| BPD‡ | 104 | 88.9 | 247 | 79.2 | 289 | 72.8 | 308 | 64.6 | 124 | 49.8 | 108 | 36.5 | 58 | 18.0 | 30 | 8.8 | 1268 | 50.5 |
| NEC | 9 | 7.7 | 47 | 15.0 | 33 | 8.3 | 42 | 8.7 | 25 | 10.0 | 32 | 10.8 | 27 | 8.4 | 15 | 4.4 | 230 | 9.1 |
| All IVH | 60 | 51.3 | 144 | 45.9 | 141 | 35.3 | 118 | 24.5 | 65 | 26.1 | 56 | 18.9 | 64 | 19.8 | 44 | 12.9 | 692 | 27.4 |
*North America (USA and Canada).
†Overall growth rate from birth to 36 weeks PMA calculated for 2344 infants.
‡Information regarding ROP was missing for one infant born at a gestational age of 24 weeks, and one infant at 25 weeks. Information regarding BPD was missing from two infants born at a gestational age of 24 weeks, two infants at 25 weeks and five infants born at 26 weeks.
BWSDS, birth weight SD score; BPD, bronchopulmonary dysplasia; IVH, intraventricular haemorrhage; Mdn, median; NEC, necrotising enterocolitis; PMA, postmenstrual age; ROP, retinopathy of prematurity; Trt, treatment for ROP; w, weeks. IQR (25th to 75th centile).