Recently we already covered that sperm can be cryopreserved for a short term in a home freezer. A new study from China has found that the long-term cryopreservation of semen does not affect its quality characteristics nor future clinical outcomes. It means that women who are incriminated with a sperm that had been frozen for up to 15 years are just as likely to get pregnant.

The research was conducted by Dr Chuan Huang of the Changsa-Hunan Sperm Bank in China. He and his team analyzed a total of 119,558 semen samples from sperm donors in China. For the study purposes, the samples were arranged in three groups: those that had been cryopreserved for between six months and five years; those kept in storage for between six and ten years; and those stored for between 11 and 15 years.

The first important finding was that sperm’s survival rate has tendency to decline over the storing period. In 15 years the survival rate has fallen from 85 per cent to 74 per cent. However, this decline was proved to have no influence on the pregnancy success rate in women using these samples for artificial insemination.

In the three storage groups respectively, there were cumulative live birth rates of 82.17 per cent, 80.21 per cent and 80 per cent. Success rates were similarly comparable when the frozen sperm samples were used in IVF, with live birth rates of 81.63, 79.11 and 73.91 per cent, respectively.

Results of the study were presented at the European Society of Human Reproduction and Embryology annual meeting in Vienna. For scientific community the results did not come as a surprise. Scientists know cases in the cattle breeding industry when a 50-year old frozen sperm was thawed and used for insemination. In the medical literature there have been a report on successful pregnancy in the US using donor sperm stored for longer than 40 years.

In Russia there is no limit on how long eggs, sperm or embryos can be frozen. In some countries, however, there is a time limit in fear that frozen cells might be at risk of DNA damage, although there has been to evidence of this. Cryopreservation is a process when biological material is frozen in liquid nitrogen and is kept at a temperature of -196 degrees Celsius in a state of suspended animation.

 

Photo by Thomas Fredberg / Science Photo Library
Based on the article by Daily Mail

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