Placental protein measurements in complicated pregnancies. I. Intrauterine growth retardation.

Maternal serum levels of human placental lactogen (hPL), schwangerschaftsprotein 1 (SP1) and pregnancy-associated plasma protein A (PAPP-A) were measured serially throughout pregnancy in 753 women who had a normal pregnancy when recruited during the second trimester. Thirty-three women were delivered of an infant with low birth-weight and with phenotypic features of intrauterine growth retardation (IUGR). The predictive value of an abnormal (less than 10th centile) hPL result (PVpos) in the identification of IUGR was between 28 and 32%, the sensitivity (36-54%) being greatest at 35 weeks gestation. The predictive value of a normal result (PVneg) was 87-96% at various stages of pregnancy, also greatest at 35 weeks gestation. For SP1, the sensitivity and predictive values were also greatest at 35 weeks gestation (PVpos, 20%; sensitivity, 32%; PVneg, 95%), but for PAPP-A these values were considerably less at all gestations. The trends in levels of hPL, SP1 and PAPP-A observed in individual patients with IUGR were not apparently related to any clinically recognizable feature of the pregnancy or the degree of fetal compromise, irrespective of whether the levels were within or outside the 80% confidence limits of the normal range or whether the levels fell from within the normal range. These data suggest that maternal hPL measurements are superior in the identification of IUGR in samples obtained at 30-35 weeks gestation.