Absence of human placental lactogen in an otherwise uneventful pregnancy.

Human placental lactogen (hPL) is commonly used in surveying the placental function during normal and pathologic pregnancies. This report describes a pregnancy where hPL could not be found in maternal serum or placental tissue. The pregnancy was in all other respects completely normal, ending with the birth of a normal baby. Some possible reasons and consequences of this unique event are discussed.