Blastocyst formation, pregnancy, and birth derived from human oocytes cryopreserved for 5 years.

OBJECTIVE

To report a live birth after the transfer of a single blastocyst derived from a human oocyte cryopreserved for 5 years.

DESIGN

Case report.

SETTING

Private assisted reproduction center.

PATIENT(S): A 39-year-old woman with tubal infertility and her partner with male-related infertility.

INTERVENTION(S): Oocyte cryopreservation (in 1.5 mol/L 1,2-propanediol and 0.3 mol/L sucrose by slow freezing-rapid thawing protocol) when the patient was 34 years old. Oocyte thawing after 5 years of cryostorage. Insemination by intracytoplasmic sperm injection of the three best surviving oocytes, according to the Italian law regulating assisted reproductive technology.

MAIN OUTCOME MEASURE(S): Oocyte survival after thawing. Fertilization, cleavage, and embryo development into blastocyst stage.

RESULT(S): Four of six mature (metaphase II) frozen oocytes survived after thawing. Three of them were injected: these three oocytes were fertilized, and one developed into a five-cell embryo on day 3. This embryo developed into blastocyst and was transferred on day 6. A healthy female neonate weighing 3,410 g was born.

CONCLUSION(S): After 5 years of storage in liquid nitrogen, cryopreserved oocytes with a slow cooling-rapid thawing protocol can develop in vitro to blastocyst stage and produce a live birth.