Placental function studies in low birth weight infants with and without dysmaturity.

Maternal blood levels of human placental lactogen and schwangerschaftsprotein 1 were measured in 51 women who delivered a growth-retarded infant. The levels were substantially lower in the 27 women whose infants were clinically dysmature than in the 24 women whose infants were small but of normal appearance. About one-half (44%) the cases of true dysmaturity had abnormal concentrations of human placental lactogen (less than 4 mg/L), whereas none of the small but normal group had values in this zone. It is concluded that biochemical tests of this type reflect dynamic aspects of placental function and not simply the overall size of the fetus and placenta.