According to a new study, long-term cryopreservation of human sperm would not greatly affect sperm viability. The research, conducted by Chuan Huang of the Changsa-Hunan sperm bank in China and presented at the 35th annual ESHRE meeting in Vienna, saw a retrospective analysis of 119,558 sperm samples taken from donors.
The same samples were divided into three groups: the cryopreserved ones for a period of between six months and five years, the cryopreserved ones from six to 10 years and the cryopreserved ones between 11 and 15 years. Considering the samples of the longest period, Huang and colleagues realized that, as a result of the thawing, the sperm survival rate was reduced by a few percentage points, settling in a range between 85% and 74%.
This is a decline, according to the same scholars, which has made little difference, however, as regards the clinical use of sperm in the context of assisted pregnancies.
According to Huang, these percentages would also be favored by the quality of the sperm preserved and the psychophysical condition of the donors. Despite these factors, according to the researchers, long-term sperm conservation by cryopreservation methods does not seem to affect birth rates.
However, many sperm banks establish strict time limits for sperm storage, up to a maximum of 10 years in some cases, although the scientific literature does not offer clear explanations and detailed research that can justify the imposition of these limits, not even with regards to any DNA damage.