Unexplained elevated maternal serum alpha-fetoprotein levels and pregnancy outcome in twins

To evaluate whether elevated maternal serum alpha-fetoprotein (MSAFP) levels in uncomplicated twin gestations are associated with an increased risk for pregnancy complications and adverse outcomes.

A retrospective data-base analysis was conducted of 267 women with twin pregnancies delivered between January 1988 and October 1994, of whom 42 had elevated MSAFP levels and 225 had normal levels. We evaluated rates of preterm delivery (defined as gestational age less than 34 weeks at delivery), birth weight less than 1500 g, twin-to-twin birth weight discordance, small for gestational age (SGA) infants (defined as birth weight below the tenth percentile for gestational age), and fetal malformations. Also assessed were potentially confounding variables such as obstetric and medical histories as well as sociodemographic factors.

Among nulliparous women, an unexplained elevation in MSAFP levels was associated with a statistically significant increased risk for preterm delivery. Among multiparous women, this association is suggested by the data, but not significantly so. An unexplained elevation in MSAFP level was also associated with a significantly increased risk for birth weight less than 1500 g, but this was related to the increased rate of preterm births. No appreciably increased risk was apparent for SGA infants, fetal malformations (other than neural tube defects and abdominal wall defects), or twin-to-twin birth weight discordance.

In twin pregnancies, an unexplained elevation in MSAFP level may increase the risk for preterm delivery but not other adverse pregnancy outcomes.