Intertwin birth weight discordance: its effects and their persistence in the psychological development of the lightest intrapair twin

Abstract

More twins are being born with intrapair birth weight discordances. Discordance in birth weight is a risk factor that can affect the development of twins, especially that of the lightest twin. However, few studies have analysed the possible consequences of birth weight discordance on the lightest twin beyond possible neonatal obstetric problems. Thus, little is known about the consequences of birth weight discordance on the psychological development of such babies. This article reviews the literature and summarizes the effects of birth weight discordance on the psychological development of the lightest intrapair twins compared with their heavier twin siblings and the persistence of these effects during their lifetime. The literature shows that the lightest intrapair twins obtain lower scores than their siblings in cognitive, verbal, and psychomotor skills. They are also more likely to have traits associated with the development of hyperactivity. These differences persist from childhood to youth. There is no information about adulthood. In conclusion, birth weight discordance has marked effects on the psychological development of intrapair lower weight twins, both in relation to the affected dimensions and the persistence of these effects over time. Further research is needed on designing early preventative interventions that would optimize the development of these children. This proposal is of relevance, given that the optimal development of all children is the basis of a society in continuous progress.