Neuromaturation of multiples.

Etiology of preterm birth and degree of maturation are the primary determinants of a preterm infant's survival and complications. Multiple gestation increases the likelihood of preterm birth but its influence on rate of maturation or complications of prematurity has been controversial, primarily because of confounding variables (e.g. race, aetiology of preterm delivery, degree of prematurity and pregnancy complications). Very low birthweight preterm multiples have virtually the same rates of neonatal mortality, complications and neuromaturation as preterm singletons of the same gestational age. There is no advantage of delivering twins or higher order multiples before 30 weeks gestation, unless a fetus decompensates in utero. Survival improves for near term intermediate-size preterm multiples while intrauterine growth decelerates and placental and fetal neuromaturation accelerate. These data and the high fetal death rate at term support delivery of multiples as soon as there is fetal lung maturity, and consideration of elective delivery of twins at 35-38 weeks gestation and triplets at 33-35 weeks gestation.