Abstract: An isolated and purified glycoprotein designated PUP-1 and functional analogs thereof are disclosed and characterized by being a progesterone induced and estradiol inhibited secretory glycoprotein from stromal cells of endometrial origin; having an N-terminal amino acid sequence as set forth in SEQ ID No:1; having a molecular weight of 70,000 daltons and an isoelectric point of 5.7; and synthesized by endometrium at the time of fertilization, early embryogenesis, and implantation. The present invention further provides a method of determining endometrial receptivity, monitoring placental physiology during gestation, and monitoring the effects of protocols to induce ovarian hyperstimulation or ovulation induction on uterine receptivity by monitoring the cyclic presence of PUP-1 in bodily fluid and tissue samples.