Successful pregnancy following blastocyst vitrification: case report.

A 32 year old woman and her 32 year old spouse were referred to our IVF programme. Following recovery of 12 mature oocytes, nine were fertilized following conventional IVF. Three fresh embryos were transferred to the uterus, but all failed to result in pregnancy. Six supernumerary embryos were cultured in vitro until day 5 in order to create blastocysts. Two grew to the blastocyst 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 retrieval cycle. Implantation resulted in a healthy pregnancy; delivery is expected in June 2000. This report documents the first successful pregnancy in Japan, achieved via blastocyst vitrification.