Clinical endpoints
Biochemical pregnancy rates were calculated as the rate of patients with positive beta-hCG 7 days post embryo transfer out of the number of patients receiving an embryo transfer. Implantation rates were calculated as the number of gestational sacs observed at vaginal ultrasound 7 weeks after transfer out of the number of transferred embryos. Clinical pregnancy rates were calculated as the rate of patients with fetus heart activity beyond 7 weeks of gestation out of the number of patients receiving an embryo transfer.