Logistic regression analysis of the relative effects of birth order and malpresentation on respiratory distress syndrome by mode of delivery
| Number of twin sibling infants | Variable | Odds ratio (95% CI) | p Value | |
| Vaginal delivery only | 247 | Birth order | 1.9 (1.2 to 2.9) | 0.005 |
| Malpresentation | 0.81 (0.4 to 1.7) | 0.6 | ||
| Caesarean delivery only | 263 | Birth order | 1.4 (0.95 to 2.1) | 0.09 |
| Malpresentation | 1.1 (0.64 to 1.9) | 0.7 | ||
| Vaginal and caesarean delivery | 510 | Birth order | 1.6 (1.2 to 2.1) | 0.001 |
| Malpresentation | 0.98 (0.65 to 1.5) | 0.9 | ||