Normal and abnormal growth of multiples

Abstract

Growth curves of twins and triplets do not support a growth restriction patterns seen in singletons. At the same time that individual members of a twin or a triplet set may be smaller than singletons of the same gestational age, only a minority are indeed SGA by singleton standards. When comparing the entire ‘fetal mass’ of a multiple pregnancy to that of singletons, multiple gestations are in fact growth promoted, and their individual smaller size are better described as growth adaptation . Data from large twin and triplet series suggest that significant birth weight discordance result from the inability of the uterine milieu to equally nurture twins. In order to promote maturity – gestational age – mild compensation in the form of size discordance begins after mid-gestation. When the uterine environment competently nurtures multiples, total birth weight increases and discordance decreases. Failed adaptation, however, may result in significant growth discordance and restriction.