Serum Levels of the Pregnancy Zone Protein During the Normal Menstrual Cycle

Abstract
The induction of the immunosuppressive serum protein PZ (pregnancy zone protein) caused by estrogens is well known; it could be expected that the variation in endogenous estrogen levels during the menstrual cycle would influence the PZ levels. Simultaneous measurement of PZ, low polar estrogens, progesterone, LH [luteinizing hormone] and FSH [follicle stimulating hormone] during normal menstrual cycles were made.