A baby has been born using sperm frozen for 21 years 鈥� a world record, say UK researchers. The healthy boy was born to a father who had his sperm frozen in 1979 before he was treated for testicular cancer at the age of 17.
鈥淲e believe this is the longest period of sperm cryopreservation resulting in a live birth reported in the scientific literature,鈥� says Elizabeth Pease, consultant in reproductive medicine at St Mary鈥檚 Hospital, Manchester, and one of the team.
鈥淭his case report provides evidence that long-term freezing can successfully preserve sperm quality and fertility,鈥� says Greg Horne, a senior embryologist at St Mary鈥檚 Hospital and team leader. 鈥淭his is important to know because semen stored by young cancer patients is taken at a time of great emotional stress when future fertility is unlikely to be an immediate priority.鈥�
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Chris Barratt, a reproductive medicine expert at Birmingham University, agrees the record-breaking birth will offer reassurance to young men undergoing chemotherapy or radiotherapy for cancer which might render them infertile.
鈥淚t鈥檚 good news for patients,鈥� he told New 杏吧原创. 鈥淚t means the flexibility is such now that if a young lad has cancer at 15, he can wait till he finds a partner 鈥� there鈥檚 no need to rush.鈥�
No time limit
The baby boy was born in 2002 after his father and mother had undergone in-vitro fertilisation. The frozen sperm was thawed and inserted into eggs to create the embryos used.
Barratt says the success is no surprise as frozen animal sperm has been thawed and used successfully up to 40 years after it was first stored. He says theoretically there is no time limit for using frozen human sperm, as the sperm simply stays inert in the freezer.
Previously, researchers had been concerned that keeping sperm frozen for very long periods could cause damage. One worry was that it would be exposed to more background radiation than sperm freshly created in the body.
Frozen sperm are suspended in an inert state, so they cannot repair any DNA damage that occurs. However, the rate of background radiation is now considered to be so low that any damage would be negligible, he says.
Barratt points out that there may even be some benefits of long-term storage, because as a man ages there is a decline in the quality of his sperm. 鈥淚n many ways this [technique] is an advantage 鈥� the baby born has the sperm DNA of a 20-year-old rather than a 40-year-old,鈥� he says.
Journal reference: Human Reproduction (vol 19, p 1448)