2. <TAB> The second cycle (BIOPSY CYCLE) will include measurements of urinary luteinizing hormone (LH) to determine the day of the LH surge. Luteinizing hormone is the hormone that causes the ovary to release the developed egg. Ovarian ultrasounds will be performed before the biopsy to determine development of the egg. Blood tests will be taken on the day of the biopsy to have an overall idea of the hormones circulating in the patient's blood. An endometrial biopsy will be taken at one of three possible times to identify endometrial products under conditions of estrogen, estrogen/progesterone, or steroid hormone withdrawal.<TAB>