Sperm donation and its application in China: a 7-year multicenter retrospective study

Exposure to Fine Particulate Matter Constituents and Human Semen Quality Decline: A Multicenter Study

Exposure to fine particulate matter (PM < 2.5 μm in diameter [PM2.5]) may accelerate human sperm quality decline, although research on this association is limited. Our objective was to investigate the relationship between exposure to the chemical constituents of PM2.5 air pollution and decreased sperm quality and to further explore the exposure-response relationship. We conducted a multicenter population-based cohort study including 78,952 semen samples from 33,234 donors at 6 provincial human sperm banks (covering central, northern, southern, eastern, and southwestern parts of China) between 2014 and 2020. Daily exposure to PM2.5 chemical composition was estimated using a deep learning model integrating a density ground-based measure network at a 1 km resolution. Linear mixed models with subject- and center-specific intercepts were used to quantify the harmful impacts of PM2.5 constituents on semen quality and explore their exposure-response relationships. Per interquartile range (IQR) increase in PM2.5 exposure levels during spermatogenesis was significantly associated with decreased sperm concentration, progressive motility, and total motility. For PM2.5 constituents, per IQR increment in Cl- (β: -0.02, 95% CI: [-0.03, -0.00]) and NO3- (β: -0.05, 95% CI: [-0.08, -0.02]) exposure was negatively associated with sperm count, while NH4+ (β: -0.03, 95% CI: [-0.06, -0.00]) was significantly linked to decreased progressive motility. These results suggest that exposure to PM2.5 chemical constituents may adversely affect human sperm quality, highlighting the urgent need to reduce PM2.5 exposure.

An analysis of the outcome of 11 712 men applying to be sperm donors in Denmark and the USA

STUDY QUESTION

Is the outcome of donor recruitment influenced by the country in which recruitment took place or the initial identity (ID)-release choice of applicants?

SUMMARY ANSWER

More applicants are accepted as donors in Denmark than in the USA and those who choose ID release are more frequently accepted than those who do not.

WHAT IS KNOWN ALREADY

The successful recruitment of sperm donors is essential to provide a range of medically assisted reproduction (MAR) procedures, which rely upon donor sperm. However, while much has been written about the medical screening and assessment of sperm donors from a safety perspective, relatively little has been written about the process of recruiting donors and how it works in practice. There are differences in demographic characteristics between donors who choose to allow their identity to be released to their donor offspring (ID release) compared to those who do not (non-ID release). These characteristics may also influence the likelihood of them being recruited.

STUDY DESIGN, SIZE, DURATION

A total of 11 712 men applied to be sperm donors at a sperm bank in Denmark and the USA during 2018 and 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Anonymized records of all donor applicants were examined to assess the number passing through (or lost) at each stage of the recruitment process. Statistical analysis was carried out to examine differences between location (Denmark or USA) and/or donor type (ID release versus non-ID release).

MAIN RESULTS AND THE ROLE OF CHANCE

Few applicants (3.79%) were accepted as donors and had samples frozen and released for use; this was higher in Denmark (6.53%) than in the USA (1.03%) (χ2 = 243.2; 1 degree of freedom (df); z = 15.60; P < 0.0001) and was higher in donors who opted at the outset to be ID release (4.70%) compared to those who did not (3.15%) (χ2 = 18.51; 1 df; z = 4.303; P < 0.0001). Most candidate donors were lost during recruitment because they: withdrew, failed to respond, did not attend an appointment, or did not return a questionnaire (54.91%); reported a disqualifying health issue or failed a screening test (17.41%); did not meet the eligibility criteria at the outset (11.71%); or did not have >5 × 106 motile sperm/ml in their post-thaw samples (11.20%). At each stage, there were statistically significant differences between countries and the donor's initial ID choice. During recruitment, some donors decided to change ID type. There were no country differences in the frequency in which this occurred (χ2 = 0.2852; 1 df; z = 0.5340; P = 0.5933), but it was more common for donors to change from non-ID release to ID release (27.19%) than the other way around (11.45%) (χ2 = 17.75; 1 df; z = 4.213; P < 0.0001), although movements in both directions did occur in both countries.

LIMITATIONS, REASONS FOR CAUTION

No information was available about the demographic characteristics of the applicants, which may also have influenced their chances of being accepted as a donor (e.g. ethnicity and age). Donor recruitment procedures may differ in other locations according to local laws or guidelines.

WIDER IMPLICATIONS OF THE FINDINGS

A better understanding of when and why candidate donors are lost in the recruitment process may help develop leaner and more efficient pathways for interested donors and sperm banks. This could ultimately increase the number of donors recruited (through enhanced information, support, and reassurance during the recruitment process) or it may reduce the financial cost to the recipients of donor sperm, thus making it more affordable to those who are ineligible for state-funded treatment.

STUDY FUNDING/COMPETING INTEREST(S)

The study received no funding from external sources. All authors are Cryos employees or members of the Cryos External Scientific Advisory Committee.

TRIAL REGISTRATION NUMBER

N/A.

Sperm mitochondrial DNA copy number in relation to semen quality: A cross-sectional study of 1164 potential sperm donors

OBJECTIVE

To investigate the association between mitochondrial DNA copy number (mtDNAcn) and semen quality.

DESIGN

A cross-sectional study.

SETTING

Hubei Province Human Sperm Bank of China (from April 2017 to July 2018).

POPULATION

A total of 1164 healthy male sperm donors with 5739 specimens.

MAIN OUTCOME MEASURES

Real-time quantitative polymerase chain reaction (RT-PCR) was used to measure sperm mtDNAcn. We also determined semen volume, concentration and motility parameters (progressive motility, nonprogressive motility and immotility).

METHODS

Mixed-effect models and general linear models were uses.

RESULTS

After adjusting for relevant confounding factors, mixed-effect models revealed diminished sperm motility (progressive and total), concentration, and total count across the quartiles of mtDNAcn (all P < 0.05). Compared with men in the lowest quartile, men in the highest quartile of mtDNAcn had lower progressive sperm motility, total motility, concentration and total count of -8.9% (95% CI -12.7% to -5.0%), -8.0% (95% CI -11.6% to -4.4%), -42.8% (95% CI -47.7% to -37.4%), and - 44.3% (95% CI -50.1% to -37.7%), respectively. These inverse dose-response relationships were further confirmed in the cubic spline models, where mtDNAcn was modelled as a continuous variable.

CONCLUSIONS

We found that mtDNAcn was inversely associated with semen quality in a dose-dependent manner. Our results provide novel clues that sperm mtDNAcn may serve as a useful predictor of human semen characteristics.

TWEETABLE ABSTRACT

Sperm mitochondrial DNA copy number was markedly associated with diminished sperm motility (progressive and total), concentration and total count.

Associations between depression, oxidative stress, and semen quality among 1,000 healthy men screened as potential sperm donors

OBJECTIVE

To explore the association between depression and semen quality and the mediating role of oxidative stress.

DESIGN

Cross-sectional study with repeated measures of semen quality.

SETTING

Human Sperm Bank of Hubei Province, People's Republic of China.

PATIENT(S)

From April 2017 to July 2018, we recruited 1,000 potential sperm donors who completed the Beck Depression Inventory questionnaire and had measures of oxidative stress biomarkers.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Severity of depression was evaluated by the Beck Depression Inventory scores (0-4, no depression; 5-13, mild depression; 14-20, moderate depression; and 21 or greater, severe depression). The urinary concentrations of 8-hydroxy-2-deoxyguanosine, 4-hydroxy-2-nonenal-mercapturic acid, and 8-iso-prostaglandin F_2α (8-isoPGF_2α) were measured to reflect oxidative stress status. Repeated semen quality parameters (n = 5,880) were examined by trained professional technicians according to the World Health Organization laboratory manual. Associations between depression, oxidative stress, and repeated measures of semen quality parameters were evaluated using linear or mixed-effects models with adjustment for potential confounders. Mediation analysis was performed to test the potential mediating role of oxidative stress.

RESULT(S)

A total of 391 (39.1%) men were classified as mild depression, 67 (6.7%) as moderate depression, and 19 (1.9%) as severe depression. Inverse dose-response relationships between severity of depression and semen quality parameters were found. Compared with men without depression (n = 523), those with severe depression had a 25.26% (95% confidence interval, -38.65%, -8.93%) lower semen volume, 37.04% (-55.37%, -11.20%) lower total sperm count, 13.57% (-23.17%, -2.78%) lower total motility, and 15.08% (-25.09%, -3.72%) lower progressive motility; men with moderate depression also had a 12.28% (-21.16%, -2.40%) lower semen volume and 23.56% (-36.50%, -7.97%) lower total sperm count. We found a positive dose-response relationship between severity of depression and urinary 8-isoPGF_2α concentrations. However, we found no evidence that the associations between depression status and semen quality were mediated by oxidative stress markers.

CONCLUSION(S)

In the study of Chinese male sperm donors, men with depression had worse semen quality parameters, including semen volume, sperm concentration, total sperm count, total motility, and progressive motility. Although depression was positively associated with urinary 8-isoPGF_2α concentrations, depression-semen quality associations were not mediated by oxidative stress.

Analysis of the screening results of 24040 potential sperm donors in a human sperm bank in Henan Province, China: a 14-year retrospective cohort study

STUDY QUESTION

Is there a relation between the characteristics of potential sperm donors and the acceptance rate of these potential donors?

SUMMARY ANSWER

A relatively higher acceptance rate was observed for potential sperm donors who were aged ≤ 35 years, were married, had children, and who had received higher education, and acceptance rates were also higher during spring and winter than summer and autumn.

WHAT IS KNOWN ALREADY

Recruiting donors to a sperm bank program is difficult and slow owing to the high rates of rejection and dropout.

STUDY DESIGN, SIZE, DURATION

A total of 24040 potential sperm donors were screened by the Henan Human Sperm Bank from 2006 to 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Potential sperm donors were recruited using the following baseline requirement: height of 168 cm or taller; age 22-45 years; currently attending or had graduated from high school or above. Men who met the criteria for age, height, and education level were invited for semen quality screening. The acceptable criteria for semen samples included liquefaction time < 60min, volume ≥ 2mL, sperm concentration ≥ 60 × 106/mL, progressive motility ≥ 60%, post-thaw motility ≥ 40%, pre-freezing total motile sperm per vial > 30 × 106/mL, post-thaw total motile sperm per vial > 12 × 106/mL, and freeze-thaw survival rate ≥ 60%. Any potential sperm donors meeting the minimum criteria for acceptable semen quality on two consecutive semen samples were scheduled for clinical assessment, physical examination, and laboratory tests. The reasons for sperm donor rejection were analyzed. The characteristics of accepted and rejected donors were compared using the chi-square test, and multivariate logistic regression analyses were conducted to identify factors associated with the acceptance rate of potential sperm donors and the positive rate of sexually transmitted diseases (STDs).

MAIN RESULTS AND THE ROLE OF CHANCE

Only 23.38% (5620/24040) of potential sperm donors were accepted. The top four reasons for rejection were suboptimal semen quality (90.27%), STDs (6.26%), dropped out (2.65%), and chromosomal abnormalities (0.35%). The most common reason for the rejection of donors with an STD was a positive test for mycoplasmas (49.05%), followed by hepatitis B virus (27.56%), Chlamydia trachomatis (4.68%), and Escherichia coli (3.03%). n this study, the acceptance rate for men aged ≤ 35 years was significantly higher than that for men aged >35 years (P < 0.05). The acceptance rates were also significantly higher for men with a higher education than for men with lower education, married men than unmarried men, and men with children than men without children (P < 0.05). Moreover, acceptance rates were significantly higher during spring and winter than during summer (P <0.05) but were not significantly higher during autumn than during summer (P >0.05).

LIMITATIONS, REASONS FOR CAUTION

This study was not performed to analyze the effect of lifestyle habits, such as alcohol consumption and cigarette smoking, on the acceptance rate of potential sperm donors.

WIDER IMPLICATIONS OF THE FINDINGS

Only a small proportion of potential sperm donors were accepted in this anonymous sperm donor program. New strategies for sperm donor recruitment may be required to improve the acceptance rate. In the future, we may have to target potential sperm donors who are aged ≤ 35 years and who received higher education in order to improve the acceptance rate.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Joint Construction Project of Henan Medical Science and Technology Research Plan under grant number LHGJ20190389. The authors report no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Physical activity and sedentary time in relation to semen quality in healthy men screened as potential sperm donors

STUDY QUESTION

Is physical activity or sedentary time associated with semen quality parameters?

SUMMARY ANSWER

Among healthy men screened as potential sperm donors, higher self-reported physical activity was associated with increased progressive and total sperm motility.

WHAT IS KNOWN ALREADY

Despite the claimed beneficial effect of moderate physical activity on semen quality, results from epidemiological studies have been inconclusive. Previous studies were mostly conducted among endurance athletes or male partners of couples who sought infertility treatment.

STUDY DESIGN, SIZE, DURATION

Healthy men screened as potential sperm donors were recruited at the Hubei Province Human Sperm Bank of China. Between April 2017 and July 2018; 746 men completed the long-form International Physical Activity Questionnaire (IPAQ) and provided repeated semen samples (n = 5252) during an approximately 6-month period.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Total metabolic equivalents (METs), moderate-to-vigorous METs and sedentary time were abstracted from the IPAQ. Sperm concentration, total sperm count, progressive motility and total motility in repeated specimens were determined by trained clinical technicians. Mixed-effect models were applied to investigate the relationships between physical activity and sedentary time and repeated measures of semen quality parameters.

MAIN RESULTS AND THE ROLE OF CHANCE

After adjusting for multiple confounders, total METs and moderate-to-vigorous METs were both positively associated with progressive and total sperm motility. Compared with men in the lowest quartiles, those in the highest quartiles of total and moderate-to-vigorous METs had increased progressive motility of 16.1% (95% CI: 6.4, 26.8%) and 17.3% (95% CI: 7.5, 27.9%), respectively, and had increased total motility of 15.2% (95% CI: 6.2, 24.9%) and 16.4% (95% CI: 7.4, 26.1%), respectively. Sedentary time was not associated with semen quality parameters.

LIMITATIONS, REASONS FOR CAUTION

The IPAQ was reported only once from study participants; measurement errors were inevitable and may have biased our results. Furthermore, although we have adjusted for various potential confounders, the possibility of unmeasured confounding cannot be fully ruled out.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings suggest that maintaining regular exercise may improve semen quality parameters among healthy, non-infertile men. Specifically, we found that higher self-reported total and moderate-to-vigorous METs were associated with improved sperm motility, which reinforces the existing evidence that physical activity may improve male reproductive health.

STUDY FUNDING/COMPETING INTEREST(S)

Y.-X.W was supported by the Initiative Postdocs Supporting Program (No. BX201700087). A.P. was supported by the National Key Research and Development Program of China (2017YFC0907504). C.-L.X. was supported by the National Key Research and Development Program of China (2016YFC1000206). The authors report no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Ambient air pollution and male fecundity: A retrospective analysis of longitudinal data from a Chinese human sperm bank (2013-2018)

Ambient air pollution has adverse effects on human health and reproduction. A number of studies have suggested a significant association between ambient air pollution and human fecundity, with most studies focusing on cross-sectional data from the general male population with single semen samples. We conducted a retrospective study in China using longitudinal analysis of repeated semen samples to investigate the association between environmental exposure parameters (e.g., PM_2.5, PM₁₀, SO₂, NO₂, CO, ground temperature, and relative humidity) and sperm quality parameters (e.g., semen volume, sperm concentration, forward motility concentration, and percentage of progressive rate) during different exposure windows (current day, 90-day preceding). Data from 686 males and 4841 semen samples collected between 2013 and 2018 at Sichuan Provincial Sperm Bank were included in a mixed-effects model analysis. The study population was young, healthy, and well-educated. The results indicate that 90-day average concentrations of PM_2.5, PM_10, and CO were negatively associated with sperm concentration and forward motility concentration, whereas 90-day average concentration of O₃ was positively associated with forward motility concentration. Between-subject variability played the dominant role in overall model variance. Our results suggest that chronic exposure to particulate matter and CO may interfere with spermatogenesis.

Association between BMI and semen quality: an observational study of 3966 sperm donors

STUDY QUESTION

What is the relationship between abnormal BMI and semen quality?

SUMMARY ANSWER

Underweight was significantly associated with lower sperm concentration, total sperm number and total motile sperm count, while overweight was significantly associated with lower semen volume, total sperm number and total motile sperm count.

WHAT IS KNOWN ALREADY

Abnormal BMI has been associated with lower semen quality, but the results remain somewhat controversial. In addition, most previous studies have focused on the influence of obesity or overweight on semen quality, and evidence on the association between underweight and semen quality is rare.

STUDY DESIGN, SIZE, DURATION

This research was an observational study investigating 3966 sperm donors from a large sperm bank in Wuhan city, China. These donors passed the screening for sperm donation and underwent 29 949 semen examinations between 1 January 2013 and 9 April 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

BMI was categorized into four groups: underweight (<18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2) and obese (≥30 kg/m2). Semen volume, sperm concentration, total sperm number, total motility, progressive motility and total motile sperm count were determined by trained clinical technicians. Linear mixed models were used to conduct dose-response analyses between BMI and semen quality parameters.

MAIN RESULTS AND THE ROLE OF CHANCE

Underweight was significantly associated with a 3.0% (95% CI: 0.1%, 5.8%), 6.7% (1.9%, 11.3%) and 7.4% (2.2%, 12.4%) reduction in sperm concentration, total sperm number and total motile sperm count, respectively. Overweight was significantly associated with a 4.2% (1.6%, 6.8%), 3.9% (0.9%, 6.9%) and 3.6% (0.2%, 6.9%) reduction in semen volume, total sperm number and total motile sperm count, respectively. Non-linear models including continuous BMI as a natural cubic spline function yielded similar results.

LIMITATIONS, REASONS FOR CAUTION

Our study subjects were sperm donors who are typically young and healthy, and therefore not representative of the general male population. Caution should be paid in generalizing our results to other populations. Furthermore, we did not measure the donors' weight repeatedly along with each semen donation; instead, we only measured it once during the screening, which may cause bias due to the variations of weight across time.

WIDER IMPLICATIONS OF THE FINDINGS

Our study provides evidence that underweight and overweight are associated with lower semen quality, and highlights the importance of maintaining a normal weight for men.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Health and Family Planning Commission of Hubei Province (Grant number WJ2015MA027), the Hubei Provincial Committee of the Communist Youth League of China, and Center for Global and Regional Environmental Research at the University of Iowa. The authors declare that there are no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Biovigilance for the Quality and Safety of Medical Products of Human Origin

Progress in science and technology in the health services has led to the development of methods of regenerating and replacing solid organs, tissues and cells, using human body components to create medical products of human origin intended for clinical use. In the activities in which products of human origin are used, however, from the point of donation and harvesting to the subsequent care of the recipient, medical products of human origin are exposed to the risk of specific complications related to the transmission of infectious diseases, and further side-effects. Biovigilance system application is a basic requirement for ensuring the quality and safety of tissues and cells intended for human use. The quality system focuses on error prevention, maintaining a consistent pattern of agreed assays for tissues and cells intended for clinical use. The implementation of quality and safety standards, the development of medical protocols and cooperation protocols between member states, the implementation of Single European Code (SEC), and the development of electronic traceability systems, all aim at vigilance and the surveillance of medical products of human origin from donation to transplantation.

Decline in semen quality among 30,636 young Chinese men from 2001 to 2015

OBJECTIVE

To provide information of semen quality among young Chinese men in the past 15 years.

DESIGN

Retrospective cross-sectional study.

SETTING

Sperm bank.

PATIENT(S)

A total of 30,636 young adult men who applied to be sperm donors at the Hunan Province Human Sperm Bank of China in 2001-2015 were included in the study.

INTERVENTION(S)

Physical examination and analysis of blood and semen samples.

MAIN OUTCOME MEASURE(S)

Semen parameters, such as semen volume, sperm concentration, total sperm count, progressively motile sperm count, sperm progressive motility, sperm morphology, and round cells.

RESULT(S)

Many of the semen parameters showed a decreasing trend over the 15-year observation period. The sperm concentration and percentage of sperm with normal morphology decreased from 68 × 10⁶/mL to 47 × 10⁶/mL and from 31.8% to 10.8%, respectively. Although sperm progressive motility showed irregular variation, the progressively motile sperm count decreased from 34 × 10⁶ to 21 × 10⁶ over the 15-year period. Furthermore, the rate of qualified donors fell from 55.78% in 2001 to 17.80% in 2015, and the rate for 2015 was approximately threefold lower than the corresponding rates in 2001.

CONCLUSION(S)

The semen quality among young Chinese men has declined over a period of 15 years, especially in terms of sperm concentration, total sperm count, sperm progressive motility, and normal morphology.

Evaluation of semen quality in 1808 university students, from Wuhan, Central China

The aim of this study was to evaluate the semen quality of university students in Wuhan, the largest city in the world in terms of the number of university students. All student sperm donors recorded in the Hubei Province Human Sperm Bank from 1 March 2010 to 31 December 2013 were screened. At last, a total of 3616 semen samples from 1808 university student sperm donors were eligible and retrospectively analyzed. Each donor's semen parameters were averaged over two samples and compared with the World Health Organization criteria, and a generalized linear regression model was used to examine several determinants of semen quality. We found that the mean and median values were 3.0 ml and 2.8 ml for semen volume, 50.2 × 10⁶ ml⁻¹ and 50.0 × 10⁶ ml⁻¹ for sperm concentration, 148.1 × 10⁶ and 142.1 × 10⁶ for total sperm count, and 58.6% and 60.0% for total sperm motility. About 85.0% of donors had parameters that were all normal. Season and duration of abstinence were critical factors affecting semen quality. We also found a decrease in sperm concentration during the 4 years observation; however, this may not be a strong evidence to confirm the declining trend of semen quality. In conclusion, semen quality of university students in Wuhan was not optimal and should be paid high attention, long-term observation and further study should be carried out to confirm the present situation.

Variability in the morphologic assessment of human sperm: use of the strict criteria recommended by the World Health Organization in 2010

OBJECTIVE

To determine the variability in the recognition of normal sperm and various sperm defects using the strict criteria recommended by the World Health Organization (5th edition, 2010).

DESIGN

Sperm morphologic assessment by three experienced evaluators.

SETTING

Image processing laboratory and reproduction research institute.

PATIENT(S)

Semen donors from a sperm bank.

INTERVENTION(S)

The morphology of 5,296 sperm was evaluated using statistical analyses of variability.

MAIN OUTCOME MEASURE(S)

The proportion and coefficients of variation (CVs) of normal sperm, defects of specific parts, and the categories of defects were measured. The degree of agreement between any two of the three evaluators was calculated. The multiple anomalies index, teratozoospermia index, sperm deformity index, and the CVs were also measured.

RESULT(S)

The CVs of normal sperm, multiple anomalies index, teratozoospermia index, and sperm deformity index were 4.80%, 4.14%, 5.75%, and 6.81%, respectively. A broader range (4.80%-132.97%) of CVs was observed for the recognition of various defects. The coefficients of the degree of agreement concerning specific morphologic parts of sperm varied (0.387-0.607), with lower relative values for the head and mid-piece than for the tail and cytoplasm.

CONCLUSION(S)

The sperm head is more difficult to evaluate than the other parts using the criteria recommended by the World Health Organization in 2010. The degree of agreement concerning specific parts and various defects varied in broad ranges. A stricter definition for each defect is needed.

Effect of pre-freezing conditions on the progressive motility recovery rate of human frozen spermatozoa

We evaluated the effects of sperm concentration, progressive motility, sperm morphology, duration of abstinence and collection season on the progressive motility recovery rate of human frozen spermatozoa to identify characteristics that predict the progressive motility recovery rate of human frozen spermatozoa and improve the protocol for sperm collecting in sperm banks. A total of 14 190 semen samples donated at Zhejiang human sperm bank of China between September 2006 and June 2011 were collected from 1624 donors. Semen was evaluated according to WHO standard procedures for sperm concentration. Progressive motility, sperm morphology, ejaculate collection season and abstinence time were recorded. After freezing and thawing, the progressive motility was assessed. Results showed that sperm concentration, progressive motility and normal morphology were significantly associated with the progressive motility recovery rate of human frozen spermatozoa. In addition, the abstinence time and collection season also significantly affected progressive motility recovery rate. Our results indicated that sperm concentration, progressive motility and normal morphology could be valuable in predicting the progressive motility recovery rate of human frozen spermatozoa. As such, progressive motility recovery may be improved by donating semen when abstinent for 3-5 days and during seasons other than summer.