Long-term sperm freezing makes no difference to live birth rates, a study has found.
Despite a time limit imposed in many countries on the freeze-storage of sperm, a large sperm bank study has shown the long-term cryopreservation of semen in a sperm bank does not affect future clinical outcomes.
The findings are based on a retrospective analysis of 119,558 semen samples from donors at the Hunan Sperm Bank in China.
The samples were arranged in three groups: those kept in cryostorage for between six months and five years, those stored for between six and 10 years, and those stored for between 11 and 15 years.
The study first found that the frozen sperm’s survival rate after thawing did decline over the 15-year study period – from 85% to 74% survival.
However, this decline made little difference to the pregnancy and live birth rate in women using these samples for donor insemination, with cumulative live birth rates of 82.17%, 80.21% and 80.00% in the three storage groups respectively.
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% in the three groups.
Results of the study are being presented at the European Society of Human Reproduction and Embryology (Eshre) annual meeting in Vienna.