Plasma human placental lactogen in late pregnancy and labor

Human placental lactogen (HPL) is a polypeptide placental hormone secreted in increasing amounts during pregnancy with both prolactin- and growth hormone-like properties. Development of a radioimmunoassay system for this hormone has allowed the authors to follow patients in late pregnancy and labor. When subjected to statistical analysis, the mean plasma HPL levels obtained showed a significant fall when the 40 week specimen is compared to those obtained in late labor. These data indicate that a change in HPL is not involved in the process of the initiation of labor. The observed change in HPL, however, reflects the relative uterine and placental ischemia of labor. The potential use of HPL as an index of placental function is discussed.