Table 1

Like and unlike sex twin pairs by stillbirth/live birth status: England and Wales 1982–91

Both stillbirths (%)1 stillbirth 1 live birth (%)Both live births (%)Total twin pairs
a Like sex pairs317 (0.6%)1294 (2.6%)47 999 (96.8%)49 610 (100%)
b Unlike sex pairs12 (0.1%)402 (1.9%)20 748 (98.0%)21 162 (100%)
a+b Total twin pairs329 (0.5%)1696 (2.4%)68 747 (97.1%)70 772 (100%)
a−b 1-150Monozygotic pairs305 (1.1%)892 (3.1%)27 251 (95.8%)28 448 (100%)
2 x b1-152Dizygotic pairs24 (0.1%)804 (1.9%)41 496 (98.0%)42 324 (100%)

  • ↵1-150 Applying the Weinberg rule that, among dizygotic twins, there are an equal number of like sex as unlike sex pairs.

  • ↵1-152 Based on the assumption that fetal death rates in unlike (dizygotic) sex pairs is the same as in like dizygotic sex pairs.