Maternal serum alpha-fetoprotein levels in triplet and quadruplet pregnancy.

Maternal serum alpha-fetoprotein (AFP) levels were higher in six triplet pregnancies and three quadruplet pregnancies than in control singleton pregnancies matched for maternal age, parity and time of gestation at which the serum sample was taken. Between 12 and 23 weeks of pregnancy, the average AFP levels among the triplet pregnancies was three times that found in the singleton pregnancies, and the level in the quadruplet pregnancies was even higher. Maternal serum AFP levels appear to be associated with the number of fetuses in utero.