Table 3 Risk factors for perinatal death among 776 twins born at the hospital
From: A prospective study of twinning and perinatal mortality in urban Guinea-Bissau
|  | N1 | Univariate analysis | Multivariate analysis N2 = 464 |
|---|---|---|---|
| Â | Â | RR (CI) | Adjusted RR (CI) |
Infant risk factors | Â | Â | Â |
 Male sex | 776 | 1.30 (1.00-1.71) | 1.38 (0.97-1.96) |
 Birth weight category | 763 |  |  |
  > = 2500g (ref) |  | 1.00 | 1.00 |
  2000-2499g |  | 1.15 (0.69-1.92) | 1.10 (0.57-2.09) |
  <2000g |  | 4.48 (3.00-6.70) | 4.24 (2.39-7.51) |
 Prematurity* | 198 | 3.78 (2.05-6.97) | - |
 Long intertwin delivery interval** | 343 | 1.47 (0.79-2.73) | - |
 Breech presentation at birth | 773 | 0.97 (0.66-1.42) | 1.26 (0.72-2.12) |
 Caesarean section | 773 | 0.99 (0.68-1.44) | 1.78 (1.06-2.99) |
 Second twin | 776 | 1.07 (0.88-1.29) | 0.97 (0.69-1.36) |
Maternal risk factors | |||
 Age < 18 years | 764 | 1.26 (0.59-2.68) | 1.53 (0.54-4.31) |
 Primigravida | 764 | 1.52 (1.07-2.15) | 0.80 (0.44-1.46) |
 HIV infection | 622 | 1.06 (0.57-2.00) | 1.09 (0.66-1.80) |
 High BP (>140/90) during pregnancy | 644 | 1.97 (1.03-3.79) | 1.77 (0.88-3.57) |
 Unawareness of twin pregnancy | 750 | 1.89 (1.26-2.85) | 1.64 (0.97-2.78) |
Socio-economic risk factors | |||
 Lack of schooling | 760 | 0.97 (0.71-1.33) | 0.89 (0.58-1.34) |
 Unmarried | 764 | 0.90 (0.66-1.23) | 1.13 (0.73-1.74) |
Exogenous risk factors | Â | Â | Â |
 Rainy season | 776 | 0.85 (0.63-1.16) | 0.91 (0.59-1.40) |