Birth of healthy twins from in vitro development of human refrozen embryos

Objective: To avoid the risk of ovarian hyperstimulation syndrome and promo te pregnancy rate by freezing pronuclear embryos at the oocyte retrieval an d using developed refrozen supernumerary embryos in the event of failed pre gnancies. Design: A case study. Setting: Private IVF center. Patient(s): Healthy infertile woman undergoing IVF treatment. Intervention(s): Slowly frozen and rapidly refrozen embryos at varying stag es of embryonic development were transferred. Main Outcome Measure(s): Survival rate of refrozen and thawed embryos; safe ty of refrozen embryo transference. Result(s): Fertilized pronuclear embryos that were frozen, thawed, and deve loped to morula embryos were subsequently vitrified, rethawed, and cultured until blastocyst formation before transfer. Healthy fraternal twins were b orn by caesarian section. The result of transfer was the novel finding of a successful delivery after the use of refrozen embryos. Conclusion(s): The transfer of refrozen supernumerary embryos resulted in s uccessful pregnancy and delivery. We will continue to investigate the safet y and efficacy of the elective freezing of all embryos as well as their ref reezing so that supernumerary embryos can be reused to avoid ovarian hypers timulation syndrome or in cases of repeated failed pregnancies. (C) 2001 by American Society for Reproductive Medicine.