Amniotic fluid human chorionic gonadotropin in late pregnancy: elevated levels in toxemia with intrauterine growth retardation.

Amniotic fluid human chorionic gonadotropin (hCG) was studied by radioimmunoassay in 88 normal pregnancies and in 48 pregnancies with toxemia either with or without intrauterine growth retardation, between 34 and 41 weeks. In normal pregnancy, no significant change in the hCG level was observed from 34 to 41 weeks, with the logarithmic mean value being 522 mU/ml. The hCG levels in amniotic fluid were markedly elevated in toxemia (logarithmic mean 1,079 mU/ml), especially when associated with intrauterine growth retardation (logarithmic mean 2,056 mU/ml). Since in intrauterine growth retardation without maternal disease the hCG levels were normal (logarithmic mean 657 mU/ml), toxemia itself may be the factor that causes elevated levels of hCG in amniotic fluid.