Plasma progesterone in women with a history of recurrent early abortions.

Basal body temperature, vaginal hormonocytology, and plasma progesterone concentrations were studied serially in consecutive menstrual cycles of 8 normal subjects and of 10 patients with a history of recurrent early abortions. The menstrual patterns and characteristics of basal body temperature of the patients did not differ significantly from those of control subjects. The mean plasma progesterone concentrations at the midluteal phase of the study cycles of three patients were below those of the lower limit of the control group (4 ng/ml). The results of this study support the conviction that an inadequate luteal phase is more likely to occur in women with a history of recurrent early abortions.