Stimulation cycles suppressed with gonadotropin-releasing hormone analog yield accelerated embryos.

A retrospective study was performed to assess embryonic development and morphology in 71 patients whose follicular stimulation was regulated after down regulation with a gonadotropin-releasing hormone analog, leuprolide acetate. The embryos were compared with those from 66 patients who did not receive agonists and who were treated during the same period. A separate group of thawed embryos cryopreserved after down regulation in 21 patients was compared with embryos frozen after conventional stimulation during the same period from 21 other patients. Eleven morphological criteria were assessed in the fresh embryos, and analyses did not reveal any differences between the groups studied. However, the rate of development of embryos obtained during down-regulated cycles was significantly higher than that of embryos developing in conventional stimulation cycles. Although no significant morphological differences could be shown between the groups of cryopreserved embryos, there was a decreased incidence of implantation of embryos from patients who were exposed to analogs. It is suggested that embryos from down-regulated cycles should be cryopreserved earlier to correct for their accelerated development.