Pregnancy-specific beta-1-glycoprotein levels in normal and toxemic pregnancy.

Maternal plasma levels of pregnancy-specific beta-1-glycoprotein (PSBG) in 166 normal and 169 toxemic pregnancies were measured by radioimmunoassay in the third trimester. Individual PSBG levels were studied in 16 women during weeks 7 through 39 of normal pregnancy. The levels were found to increase as pregnancy progressed. During the third trimester neither normal nor toxemic pregnancies showed any circadian rhythm in PSBG levels. In toxemic pregnancies low PSBG values were seen mainly in cases with intrauterine growth retardation (IUGR). Plasma PSBG concentrations at weeks 39-40 in toxemic patients correlated positively with placental weight. No such correlation was found in normal or toxemic pregnancies at 37-38 weeks or in either group between PSBG level and infant birth weight, birth length, or Apgar score. In toxemic pregnancies with low PSBG values during the last trimester, birth weights were somewhat lower than in those with normal levels. Thus, low levels of maternal plasma PSBG may reflect IUGR, but will be of little value for assessment of fetal condition at birth.