Relative risk* of neonatal death among singleton infants with birthweights of at least 2500 g in maternity units of different size
| Size of maternity unit† (No of births per year) | Deliveries (n) | Relative risk* | 95% confidence interval |
|---|---|---|---|
| ⩽100 | 26 486 | 2.1 | 1.6–2.8 |
| 101–500 | 197 478 | 1.7 | 1.4–2.0 |
| 501–1000 | 203 735 | 1.5 | 1.3–1.8 |
| 1001–2000 | 403 506 | 1.5 | 1.3–1.8 |
| 2001–3000 | 181 959 | 1.0 | ref. |
| >3000 | 241 120 | 1.7 | 1.4–2.0 |
3-150 Relative risks were approximated by odds ratios in logistic regression models adjusted for year of birth, congenital anomalies, maternal disease during pregnancy, breech presentation, multiparas, hydramnios or oligohydramnios, premature rupture of the membranes and placenta previa.
3-151 There was an overall significant difference in mortality between maternity units with a p value of less than 0.0001.