Table 1. Birthweight and gestational age of twins according to variables.
| Variables | No. of cases (%) | Mean of birthweight (g) (s.d.) | Gestational age (weeks) (s.d.) |
|---|---|---|---|
| Total of twin births | 22507(100.0) | 2384.8(489.1) | 35.8(2.4) |
| Sex | |||
| Male twin | 11861(52.7) | 2424.3(501.8) | 35.8(2.4) |
| Female twin | 10646(47.3) | 2328.2(470.7)** | 36.0(2.3)** |
| Like-sexed female | 7178(31.9) | 2334.2(459.6) | 36.0(2.3) |
| Like-sexed male | 8419(37.4) | 2402.2(498.1)a,b | 35.8(2.4)a |
| Unlike-sexed | 6910(30.7) | 2427.7(479.2)a,b | 35.8(2.3)a |
| Method of delivery | |||
| Caesarean section | 20376(90.5) | 2439.6(444.5) | 36.1(2.02) |
| Virginal | 2131(9.4) | 1898.3(547.2)** | 33.3(3.4)** |
| Birth order | |||
| First | 11329(50.3) | 2423.5(480.7) | 35.9(2.3) |
| Second | 11178(49.7) | 2353.2(480.5)** | 35.9(2.3) |
| Parity | |||
| Primipara | 12891(57.3) | 2385.2(476.6) | 35.9(2.3) |
| Multipara | 9616(43.7) | 2393.2(488.8) | 35.8(2.4) |
| Preterm birth (<37 weeks) | |||
| Yes | 12500(55.5) | 2197.5(476.7) | 34.3(2.0) |
| No | 10007(44.5) | 2627.3(368.5)** | 37.7(1.0)** |
| Low birthweight (<2500g) | |||
| Yes | 11871(52.7) | 2038.3(353.8) | 34.9(2.5) |
| No | 10636(47.3) | 2780.8(245.1)** | 37.0(1.4)** |
aMeans both unlike-sexed and like-sexed male compared to like-sexed female, P < 0.01.
bMeans unlike-sexed compared to like-sexed male, P < 0.01; **P < 0.01.