Fetal growth achievement and elevated maternal serum alpha-fetoprotein.

Maternal serum alpha-fetoprotein (AFP) was measured by radioimmunoassay in 7223 unselected patients between 16 and 20 weeks gestation. In 141 patients an elevated AFP level (greater than 2.5 multiples of the median for gestation) was found in the absence of a primary cause. When the birthweights of the 137 liveborn infants were corrected for maternal height and weight, sex and birth rank, 37 (27%) fell below the 10th centile of normal birthweight standards. No excess of premature deliveries was found, but there was a significant association with primiparity. Patients delivered of their second infant showed a significant decrement in mean birthweight when compared with their first-born infants and with a matched control group (normal maternal serum AFP levels). There was a highly significant association between elevated serum AFP and subsequent placental abruption.