Aaby P, Pison G, Desgrées du Loû A, Andersen M
Epidemiology Research Unit, Danish Epidemiology Science Centre, Statens Seruminstitut, Copenhagen.
Epidemiology. 1995 Jul;6(4):419-22. doi: 10.1097/00001648-199507000-00016.
Twins have been registered prospectively for 12-22 years in 42 small villages in the Bandafassi area of Eastern Senegal. We studied 98 pairs of twins to test whether twins in opposite-sex pairs have higher postneonatal mortality than same-sex twins. Neonatal mortality for twins was 41.3%; mortality for infants and for children under age 5 years was 53.0% and 66.8%, respectively. Neonatal mortality was identical for same-sex and opposite-sex twin pairs, but much higher for boys than girls [relative risk = 1.8; 95% confidence interval (CI) = 1.2-2.6]. There was clustering of double neonatal deaths for all types of twins. In the postneonatal period, female-female twins had lower mortality than other twin types. Twins had higher post-neonatal mortality as long as the co-twin was alive [mortality rate ratio (MR) = 2.6; 95% CI = 1.0-6.7]. Girls had excess mortality when the co-twin was of the opposite sex (MR = 4.3; 95% CI = 1.2-15.3), whereas there was no difference for boys. In conclusion, contact with a co-twin of the opposite sex increased child mortality for female twins. Our data are not sufficient to determine whether this difference is specific for girls or applies to boys as well.
在塞内加尔东部班达法西地区的42个小村庄，对双胞胎进行了为期12至22年的前瞻性登记。我们研究了98对双胞胎，以测试异性双胞胎的新生儿后期死亡率是否高于同性双胞胎。双胞胎的新生儿死亡率为41.3%；婴儿和5岁以下儿童的死亡率分别为53.0%和66.8%。同性和异性双胞胎对的新生儿死亡率相同，但男孩的死亡率远高于女孩[相对风险=1.8；95%置信区间（CI）=1.2 - 2.6]。所有类型的双胞胎都存在双新生儿死亡的聚集现象。在新生儿后期，女性 - 女性双胞胎的死亡率低于其他双胞胎类型。只要同胞双胞胎存活，双胞胎的新生儿后期死亡率就较高[死亡率比（MR）=2.6；95% CI =1.0 - 6.7]。当同胞双胞胎为异性时，女孩的死亡率过高（MR =4.3；95% CI =1.2 - 15.3），而男孩则没有差异。总之，与异性同胞双胞胎接触会增加女性双胞胎的儿童死亡率。我们的数据不足以确定这种差异是女孩特有的，还是也适用于男孩。
