Serum levels of placental alkaline phosphatase in high-risk pregnancies.

A recently developed radioimmunoassay (RIA) for placental alkaline phosphatase (paf) was used to estimate the maternal serum levels of the enzyme in 51 women with various complications of pregnancy. The results were compared with a reference group of 242 women with apparently normal pregnancies. Women with intrauterine growth retardation (IUGR) or severe or mild preeclampsia had significantly low weight of the fetoplacental unit. Simultaneous determinations of PAF in maternal serum and the urinary total estrogen/24 hr gave a clear differentiation of the IUGR group from the other pregnancies at risk. All PAF values from risk pregnancies were below the mean values of normal pregnancy.