Pregnancy-specific beta 1-glycoprotein (SP1) in serum from women with pregnancies complicated by intrauterine growth retardation.

Serum concentrations of pregnancy-specific beta 1-glycoprotein (SP1) were measured by nephelometry in 37 women with single pregnancies complicated by intrauterine growth retardation (IUGR). Sixty-seven blood samples were examined for their contents of SP1 in pregnancy weeks 29 to 40. The SP1 values were compared with those obtained in a cross-sectional study of 323 women and a serial study of 21 women (210 samples) with uncomplicated single pregnancies. It was found that a serum SP1 value below 80 mg/l in a single blood sample drawn in pregnancy weeks 32 to 34 had a predictive value of 50% for IUGR and a value above or at 80 mg/l had a value of 93% for predicting a normal infant birth weight. Serial samples from individual women with uncomplicated single pregnancies showed an average increase in the SP1 concentration of 49% from pregnancy weeks 30 to 36. In serial samples from six women with IUGR infants there was no such increase, or a decrease occurred. It is concluded that SP1 measurements in maternal serum are valuable for the detection and monitoring of pregnancies complicated by IUGR.