Birthweight specific cerebral palsy (CP) prevalence in twins both of whom survive infancy (Twins Early Development Study data)
| Birthweight group | No of survivors | No of responders (response rate) | No with CP | CP prevalence/1000 |
|---|---|---|---|---|
| Values in parentheses are percentages. Like-sex compared with unlike-sex Mantel-Haenszel weighted relative risk 1.26 (95% CI 0.71 to 2.22); not significant. | ||||
| Like sex | ||||
| Not stated | 327 | 212 (65) | 1 | 4.7 |
| <1000 g | 199 | 128 (64) | 3 | 23.4 |
| 1000–1499 g | 1118 | 610 (55) | 4 | 6.6 |
| 1500–1999 g | 2997 | 1632 (54) | 12 | 7.4 |
| 2000–2499 g | 6565 | 4093 (62) | 11 | 2.7 |
| ≥2500 g | 10250 | 6001 (59) | 13 | 2.2 |
| All birth weights | 21456 | 12676 (59) | 44 | 3.5 |
| Unlike sex | ||||
| Not stated | 145 | 91 (63) | 0 | – |
| <1000 g | 118 | 63 (53) | 2 | 31.7 |
| 1000–1499 g | 450 | 227 (50) | 3 | 13.2 |
| 1500–1999 g | 1251 | 694 (55) | 3 | 4.3 |
| 2000–2499 g | 3031 | 1829 (60) | 4 | 2.2 |
| ≥2500 g | 5527 | 3174 (57) | 4 | 1.3 |
| All birth weights | 10522 | 6078 (58) | 16 | 2.6 |