Placental proteins in the normal menstrual cycle, in occult pregnancy and in early normal pregnancy in the same subject.

Assays of SP1 and of hCG were done in three successive menstrual cycles in a woman undergoing artificial insemination from a donor. The day of ovulation was determined by basal body temperature, and by assays of oestradiol and progesterone. In the first cycle no placental proteins were detected, in the second cycle there was a transient peak of SP1 and hCG 4 days after ovulation. In the third cycle both proteins were first detected 12 days after ovulation, then increased rapidly in concentration and the patient went on to a normal pregnancy.