Embryo Cryopreservation Reaches 20 Year Milestone

Embryo Cryopreservation Reaches 20 Year Milestone

March 02, 2004
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Did you know that 343 babies were born as a result of assisted reproduction procedures performed at Pacific Fertility Center in 2002? Of these 343 babies, 98 or 28.6%, were babies conceived after having been stored as a frozen embryo.

This year marks the 20th anniversary of the first successful birth that resulted from human embryo cryopreservation. Since then, thousands of babies have been born worldwide after having undergone embryo cryopreservation. Freezing of excess good quality embryos allows for the transfer of fewer embryos in the stimulated IVF cycle and therefore ensures fewer high-order (triplets or more) multiple births. This process provides patients with a "back-up" should the initial fresh embryo transfer not result in a pregnancy. It is a much lower cost procedure than starting IVF all over again and often is performed with minimal medications. Frozen embryo transfers (FET) have allowed many of our patients to achieve more than one pregnancy from a single cycle of ovarian stimulation.

How safe is embryo cryopreservation? Even after 20 years, there are few studies in the scientific and medical literature concerning outcomes after embryo cryopreservation. However, the few studies that have been published are thus far reassuring.

The four largest studies performed on children conceived after embryo freezing have been done in England, France, Greece and Sweden. In all of these, the authors reported no significant difference in minor or major malformation rates in babies compared to fresh IVF embryo transfers or spontaneously conceived babies. The largest was the Swedish study, which followed 255 children born after embryo cryopreservation up to 18 months of age. Researchers compared them to 255 children born stimulated IVF cycle and therefore ensures fewer high-order (triplets or more) multiple births. This process provides patients with a "back-up" should the initial fresh embryo transfer not result in a pregnancy. It is a much lower cost procedure than starting IVF all over again and often is performed with minimal medications. Frozen embryo transfers (FET) have allowed many of our patients to achieve more than one pregnancy from a single cycle of ovarian stimulation.

How safe is embryo cryopreservation? Even after 20 years, there are few studies in the scientific and medical literature concerning outcomes after embryo cryopreservation. However, the few studies that have been published are thus far reassuring. The four largest studies performed on children conceived after embryo freezing have been done in England, France, Greece and Sweden. In all of these, the authors reported no significant difference in minor or major mal-formation rates in babies compared to fresh IVF embryo transfers or spontaneously conceived babies. The largest was the Swedish study, which followed 255 children born after embryo cryopreservation up to 18 months of age. Researchers compared them to 255 children born. The longest-term follow-up was conducted in the French study, which followed 82 children, aged 1-9, born after cryopreservation as embryos. The total malformation rate was 3.4%. Incidence of medical and surgical illness was not excessive and scholastic performance in the older children was as expected.

What is the longest time an embryo can remain frozen and still be viable? Just this month, a clinic in Israel reported the birth of healthy twins from a transfer of frozen-thawed embryos that had been cryopreserved for 12 years. Embryos, once frozen, may have unlimited potential for viability, as long as they remain at the extremely low temperatures of liquid nitrogen storage.

At Pacific Fertility Center, we are very proud of our record of success with frozen embryo transfers. We see many healthy children at baby visits that were once stored at PFC as frozen embryos. We believe that the data on safety is reassuring. We see cryopreservation as yet another way for patients to achieve healthy pregnancies through assisted reproduction.

References:

Postnatal growth and health in children born after cryopreservation as embryos. Wennerholm UB, Albertsson-Wikland K, Bergh C, Hamberger L, Niklasson A, Nilsson L, Thiringer K, Wennergren M, Wikland M, Borres MP. Lancet. 1998 Apr 11;351(9109):1085-90.

Perinatal outcome and follow-up of 82 children aged 1-9 years old conceived from cryopreserved embryos. Olivennes F, Schneider Z, Remy V, Blanchet V, Kerbrat V, Fanchin R, Hazout A, Glissant M, Fernandez H, Dehan M, Frydman R. Hum Reprod. 1996 Jul;11(7):1565-8.

Minor congenital anomalies, major congenital malformations and development in children conceived from cryopreserved embryos. Sutcliffe AG, D’Souza SW, Cadman J, Richards B, McKinlay IA, Lieberman B. Hum Reprod. 1995 Dec;10(12):3332-7.

Follow-up of children conceived from cryopreserved embryos. Sutcliffe AG. Mol Cell Endocrinol. 2000 Nov 27;169(1-2):91-3.

Outcome in children from cryopreserved embryos. Sutcliffe AG, D’Souza SW, Cadman J, Richards B, McKinlay IA, Lieberman B. St Mary’s Hospital, Manchester. Arch Dis Child. 1995 Apr;72(4):290-3.

Pregnancy and child outcome after assisted reproduction techniques. Tarlatzis BC, Grimbizis G. Hum Reprod. 1999 Sep;14 Suppl 1:231-42.

Twin delivery following 12 years of human embryo cryopreservation: case report. Revel A, Safran A, Laufer N, Lewin A, Reubinov BE, Simon A. Hum Reprod. 2004 Feb;19(2):328-9.

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