Is it normal for multiples to be smaller than singletons?

This section discusses fetal growth in multiple pregnancy from various perspectives. Whereas the entire ‘fetal mass’ of a multiple pregnancy can exceed the 90th birth weight percentile of a singleton of the same gestational age, the individual fetuses might exhibit growth patterns compatible with adaptation to the limited uterine environment. Adaptation can take the form of relative growth restriction (i.e. discordance), whereby not all fetuses show a decelerating growth pattern. When adaptation fails, fetal growth is genuinely restricted. However, even in cases with significant discordance, about 40% of the smaller twins weigh above the 10th birth weight percentile. The key in these circumstances might be found in the ability to recognize the transition from the physiologic adaptation into the pathologic process of growth restriction.