Mortality of twin and singleton live births under 30 weeks' gestation – a population based study

Abstract

Objective: To determine the mortality rates of live born twins compared to singletons of less than 30 weeks' gestation in relation to gestational age, mode of delivery and year of birth in a geographically defined population.

Study Design: We compared the early neonatal, late neonatal and infant death rates in 479 twin babies and 1538 singletons, live born between 23-29 completed weeks of gestation in the North of England over two epochs, 1998 – 2001, and 2002 – 2005.

Results: The twins and singletons had similar mortality rates except at the extreme of gestation (23-25 weeks) where twins had higher infant mortality (Odds Ratio 2.04 [95%CI 1.37 – 3.02]). This higher rate was attributable to early and late neonatal deaths (OR 1.86 [95%CI 1.28-2.72] and 2.11 [95%CI 1.13 – 3.94] respectively). When analysed in two epochs, the excess mortality was confined to babies born in 1998 – 2001. There was no effect of gender or chorionicity.

Conclusions: The excess mortality among twins of less than 30 weeks’ gestation was confined to neonatal deaths among babies of 25 weeks or less, and to the earlier epoch (1998 – 2001). In the modern era, there appears to be no excess mortality in neonates less than 30 weeks' gestation when compared with singletons.