[Detection of the early pregnancy factor (EPF) in the serum of patients with questionable pregnancy].

The early pregnancy factor (EPF) has been detected in sera of 24 women with a doubtful pregnancy by means of the rosette inhibition test using a horse antihuman lymphocyte serum. In all sera of women with an intact early pregnancy the EPF was found, furthermore in a pregnancy ending as abortion and two cases of an Arias Stella phenomenon. In non-pregnant patients the EPF was not detectable with exception of two patients under medication and one patient suffering from dysmenorrhea membranacea.