Long-term neurodevelopmental outcome in discordant twin : A nationwide population-based study in South Korea

Abstract

Objective Discordant twin is associated with increased perinatal mortality and/or morbidities. The long-term neurodevelopmental outcome has been evaluated in a few studies with small number of cases and the results are conflicting. In this nationwide population-based study, we aimed to evaluate the long-term neurodevelopmental outcomes between the birthweight discordant twin (≥20%) and concordant twins, and between the larger and the smaller twin within the pairs.

Study Design This retrospective observational cohort study included term twin neonates born between 2007 and 2010 by merging the databases of the Korea National Health Insurance claims and National Health Screening Program for Infants and Children. Subjects were divided into 2 groups according to the inter-twin birthweight discordancy (Group A, discordancy < 20%; Group B, discordancy ≥20%). The risk of adverse long-term neurodevelopmental outcome was compared between the two groups, and we further analyzed the risk within twin pairs. The adverse long-term neurodevelopmental outcome was defined as the presence of at least one of the followings: Motor developmental delay, cognitive developmental delay, autism spectrum/attention deficit hyperactivity disorders, tics/stereotypic behavior or epileptic seizures/febrile seizure.

Results During the study period, a total of 18,788 twin neonates were included and the frequency of birthweight discordancy was 18% (3422/18788). The risk of adverse long-term neurodevelopmental outcome was significantly higher in discordant twin neonates (Group B) than concordant twins (Group A) [32.42% vs. 35.48%, p=0.0006, Table 1]. Within concordant twins, the adverse neurodevelopmental outcome was not different between twin pairs. However, smaller twin had increased risk for adverse long-term neurodevelopmental outcome than larger twin within discordant twins [Table 2].

Conclusion The inter-twin birthweight discordancy was associated with adverse long-term neurodevelopmental outcome. Within discordant twin pairs, smaller neonates were at more increased risk of adverse long-term neurodevelopmental outcome than larger neonates.