Sex differences and sustained excess in mortality among discordant twins in Matlab, Bangladesh: 1977-1985.

This paper reports findings from a study that compared survival of 204 pairs of liveborn twins discordant for sex and a random sample of 2371 singleton live births from the same population in Matlab, Bangladesh during the period 1977-1985. The discordant twins showed no evidence of sex differential in neonatal survival. They had neonatal mortality of 287 and infant mortality of 468, both per 1000 live births. These rates were respectively five and four times the rate for singletons in the study. Survival from 12 months through age nine years was similar overall for both discordant twins and singletons for each sex. However, higher female than male mortality was present among discordant twins after the first few months of life. This differential was most prominent during the second year of life and appeared wider than that observed for the singletons.