Serum Placental Lactogen (HPL) Levels as an Index of Placental Function

Abstract
A rapid and reproducible radioimmunoassay for serum placental lactogen (HPL) has been developed that permits the endocrine function of the placenta to be quantitated and the progress of gestation followed. Normal levels in the third trimester (over 32 weeks) are 6.8±2.1 μg per milliliter. There is a highly significant correlation between HPL levels and placental weight. The rate and direction of changes in HPL levels in maternal serum appears to be a sensitive indicator of placental function. High levels were noted in diabetic pregnancies, and low levels with placental insufficiency. The relatively large quantities of HPL present, its autonomous production by the placenta and its short half-life combine to make its measurement of practical value in the management of high-risk pregnancies.