Table 2.
Subgroup analysis according to birthweight standard and neonatal mortality, where possible, for study quality, year of birth of study population, location of study, and singleton population
| Birth weight standard | Number of studies | Subgroup | OR (95% CI) | Estimated prediction interval (EPI) | I2, τ2 |
|---|---|---|---|---|---|
| Neonatal death | |||||
| Birthweight <1.5 kg | 331,46,48 | High-quality studies | 53.29 (30.08–94.39) | – | I2 = 0, τ2 = 0 |
| Birthweight <1.5 kg | 231,32 | Singletons | 41.85 (16.53–105.94) | – | I2 = 0, τ2 = 0 |
| Birthweight <2.5 kg | 431,32,43,52 | Singletons | 8.39 (4.90–14.36) | 0.86–81.36 | I2 = 81, τ2 = 0.20 |
| Birthweight <2.5 kg | 531,43,45,46,48 | High-quality studies | 8.15 (5.76–11.54) | 2.40–27.66 | I2 = 80, τ2 = 0.12 |
| Birthweight <2.5 kg | 246,48 | Year of birth ≥ 1990 | 9.74 (5.31–17.86) | – | I2 = 91, τ2 = 0.17 |
| Population chart <10th centile | 67,34,36,38,40,47 | Singletons | 4.03 (3.88–4.18) | – | I2 = 0, τ2 = 0 |
| Population chart <10th centile | 87,33,34,36,40,50,51 | Year of birth ≥ 1990 | 4.23 (3.73–4.81) | 3.23–5.55 | I2 = 31, τ2 = 0.01 |
| Population chart <10th centile | 47,36,47,50 | Congenital anomalies excluded | 4.01 (3.86–4.16) | – | I2 = 0, τ2 = 0 |
| Population chart <10th centile | 67,34,36,47,50,51 | Studies in USA/Europe | 4.04 (3.89–4.19) | – | I2 = 0, τ2 = 0 |