Sperm quality affected by season, abstinence time
MedWire News: Sperm banks should collect semen donations outside of the summer season and when men have remained abstinent for 3-5 days, according to study findings.
Authors of the research found that progressive motility recovery of human frozen spermatozoa may be improved by following these measures.
It is well known that cryopreservation of human semen results in declined motility, structural damage, and penetration potential after thawing, they explain. Numerous studies have evaluated various techniques for improving the recovery rate, but the relationship between pre-frozen conditions like semen characteristics, duration of abstinence, and seasons remain unclear.
"Predicting semen samples according to properties and timing of donations can potentially serve to avoid the test evaluating post-thaw progressive motility and thus reduce waste of semen samples and workload of sperm bank technicians," say Cheng Liang Xiong (Huazhong University of Science and Technology, Wuhan, China) and colleagues.
For the study, the researchers evaluated 14,190 semen samples from 1624 donors at Zhejiang human sperm bank of China during 2006-2011. Semen was evaluated according to World Health Organization standard procedures for sperm concentration.
In addition, the team recorded progressive motility, sperm morphology, ejaculate collection season, and abstinence time prior to donation. Progressive motility was then assessed following freezing and thawing.
Prior to freezing, the average sperm concentration was 88.4x106 ml/L, with an average progressive motility of 57.5% that decreased to 39.5% after thawing. The average normal morphology was 16.7% among all samples.
Findings showed that the progressive motility recovery rate of frozen spermatozoa rose significantly with increasing sperm concentration, from 63.8% to 74.8% for sperm concentrations ranging from 60x106 ml/L or less to over 120x106 ml/L.
Similarly, the progressive motility recovery rate rose significantly in line with increasing progressive motility recovery rates, from 66.5% to 69% for progressive motility of 50% or less to over 60%.
Percentage normal morphology was also found to affect the progressive motility recovery rate, which rose from 53.0% to 80.6% for percentage normal morphology of 10% or less to over 25%.
Correlation analysis confirmed that sperm concentration, progressive motility rate, and percentage normal morphology were significantly and independently correlated with sperm progressive motility.
Progressive motility rate was significantly greater among individuals who abstained for 3-5 days (68.4-70.3%) compared with those who abstained for 6 or 7 days (65.9 and 63.7%).
Analysis of the impact of seasons on progressive motility recovery rate revealed that this was lowest in semen donated in summer (June to August; 67.1%) compared with spring (March to May; 69.2%), autumn (September to November; 69.0%), and winter (December to February; 69.2%).
"Further investigation is required to confirm these findings, and it is necessary to evaluate multiple factors simultaneously in future studies," conclude the authors in Andrologia.
By Ingrid Grasmo