A study of early fetal growth patterns in twin pairs

The relationships of sitting heights and body weights of fetal twin pairs were analyzed in comparison with established growth rate standards of singleton fetuses. The apparent rate of growth of individual twins scattered around the average growth curve in the same manner as singletons. In contrast, members of 12 twin pairs with < 125 mm sitting heights, were closely similar in terms of bodily dimensions. Among the 7 pairs with crown-rump lengths of > 125 mm, 4 were discordant, suggesting a deceleration of growth in one of the twin fetuses, starting after the 18th week of gestation.