Successful pregnancy following blastocyst vitrification

A 32 year old woman and her 32 year old spouse were referred to our IVF pro gramme. Following recovery of 12 mature oocytes, nine were fertilized follo wing conventional IVF, Three fresh embryos were transferred to the uterus, but all failed to result in pregnancy. Six supernumerary embryos were cultu red in vitro until day 5 in order to create blastocysts, Two grew to the bl astocyst stage and were vitrified using a modification of a previous method . Two blastocysts survived the freeze-thaw process and were transferred to the patient's uterus during a natural cycle, 3 months after the previous re trieval cycle. Implantation resulted in a healthy pregnancy; delivery is ex pected in June 2000, This report documents the first successful pregnancy i n Japan, achieved via blastocyst vitrification.