Maternal serum-alpha-fetoprotein and low birth-weight.

High maternal serum-alpha-fetoprotein (A.F.P.) concentrations in the first half of pregnancy were associated with prematurity and high perinatal mortality. 94 singleton pregnancies without neural-tube defects but with A.F.P. levels equal to or greater than three times the normal median resulted in the birth of infants weighing, on average, 357 g less than controls (P less than 0-001). The mean head circumference of the infants was also smaller than that of the controls. The 1 stillbirth and 3 neonatal deaths yielded a mortality-rate more than three and a half times that for singleton births without neural-tube defects at the same hospital in the years 1974-76. The results suggest that some pregnant women who will deliver low-birth-weight infants at high risk of perinatal death may be identified by means of serum-A.F.P. measurement early in pregnancy.