Plasma human placental lactogen, oxytocinase, and placental phosphatase in normal and toxemic pregnancies

A total of 625 serum samples were drawn from 400 normal and 225 hypertensive toxemic pregnant women. Each sample was simultaneously assayed for its human placental lactogen (HPL), oxytocinase (O), and placental phosphatase (PP) concentration. In addition, accurate placental and infant birth weights were determined in those cases where the serum sample was obtained within 14 days of delivery. The results showed a significant rise and correlation of each of the three proteins with increasing weeks of gestation. Although the infant birth weight was unrelated to the serum level of the three proteins, both the HPL and O concentrations were significantly correlated with the placental weight in the normal pregnancies. In both types of pregnancies, the concentration of O was significantly related to that of PP and this was also true for HPL and O and HPL and PP. In all instances O was more strongly related than PP. In the toxemic pregnancies there was a higher O and lower PP level than in normal gestations. These data suggest that placental enzyme measurements, especially O, could be clinically helpful in monitoring high-risk pregnancies.