Epidemiology of Periviable Births: The Impact and Neonatal Outcomes of Twin Pregnancy.

This article discusses a study that estimated the prevalence of twin live births in the United States that were delivered in the periviable (20-25 weeks) gestational age, and compared changes in twin neonatal mortality and morbidity rates between 2005 and 2013 overall, and at periviable gestations. Although the decline in twin neonatal mortality rates at 23 and 24 weeks is encouraging, and suggests advancement in the neonatal care of these extremely small twins, the concomitant increase in neonatal morbidity at 23 weeks is concerning. Efforts to understand if twins delivered at periviable gestations suffer from long-term consequences of neurodevelopmental and cognitive deficits remain important.