Once pregnancy is confirmed progesterone support will be continued until 11.6 weeks three times a day. Blood samples and sonographic studies will be done as needed until embryo transfer. HCG, progesterone and estradiol will be measured 14 days after embryo transfer and 16-17 days after should a pregnancy be detected. An ultrasound will be performed at 5-6 weeks to confirm the presence of a gestational sac and at 6-7 weeks to confirm a heartbeat. Data will be collected until pregnancy termination or delivery.