Patients who have undergone a synthetic endometrial proliferation cycle in preparation for an embryo transfer that were identified as having a proliferative phase defect will serve as the subjects. Normal, healthy patients who are undergoing infertility treatment for single gene disorder, family balancing, or male factor infertility will serve as controls. The study will occur as part of a cryosynthetic preparatory cycle prior to embryo transfer. There will be 10 cases and 10 controls recruited for participation in the study.