Association of abstinence time with semen quality and fertility outcomes: a systematic review and dose-response meta-analysis

Impact of physical activity on semen quality: a review of current evidence

A growing global trend indicates a decline in semen quality, with a lack of physical activity identified as one of the contributing factors. Exercise is medication, and numerous studies have explored its effects on semen quality. However, there is no consensus on the most effective type and intensity of exercise for improving semen quality, owing to inconsistent findings across studies. These discrepancies may be attributable to variations in study populations (e.g., healthy versus infertile individuals) and research methodologies (e.g., observational versus interventional studies). This paper reviews the existing literature from the databases PubMed, Web of Science, and Google Scholar, reclassifying articles on their subject and research designs to delineate the relationship between exercise and semen quality. It also summarizes the mechanisms through which exercise influences semen quality, including hormonal regulation, oxidative stress, and inflammatory factors.

Ejaculatory abstinence duration impacts semen parameters: Insights from a retrospective analysis in male infertility on 23,527 analyses

Purpose

Ejaculatory abstinence (EA) duration is recognized to impact semen parameters. This study aims to evaluate the effects of varying EA durations on semen quality parameters, distinguishing between normospermic and sub-fertile men, and to provide insights into tailored abstinence recommendations for improved fertility outcomes.

Methods

We retrospectively analyzed 23,527 semen samples from men undergoing infertility evaluation from 2013 to 2024. Semen parameters, including sperm concentration, motility, and morphology, were assessed post-abstinence (2-7 days) according to WHO guidelines. Group differences were analyzed, focusing on sperm parameters across abstinence periods in normospermic versus patients with sperm abnormalities.

Results

In normospermic patients we found a trend increase from day 1 to day 7 of abstinence time regarding total sperm count (million) (92.4 vs. 191.1; p<0.01), sperm concentration (million/ml) (44.5 vs. 72.0; p<0.01) and morphology (6 vs. 12.5; p= 0.03) but not regarding motility (A+B) (50.0% vs. 48.0%; p=0.43). Conversely, in the population of patients with sperm abnormality, we found a significant trend increase from day 1 to day 7 of TSC (16.38 vs. 56.0; p<0.01), sperm concentration (million/ml) (8.0 vs. 18.0; p<0.01) and morphology (3.0 vs. 5.0; p<0.01). Interestingly, we found a significant trend decrease of motility (A+B) (28.0% vs. 21.0%; p<0.01) and pH (8.1 vs. 7.9; p<0.01) In patients affected by asthenospermia, motility (A+B) dropped significantly from day 1 to day 7 (11.8% vs. 6.1%; p<0.01) and also in patients with teratospermia morphology dropped significantly (2.13% vs. 1.26%; p<0.01).

Conclusion

The findings support the use of tailored abstinence guidelines to optimize semen quality based on patient-specific semen profiles, with normospermic men benefiting from longer abstinence durations to increase concentrations, while patients with motility or morphology impairments, may benefit from shorter abstinence periods to mitigate sperm quality declines.

Mitochondrial activator BGP-15 protects sperm quality against oxidative damage and improves embryo developmental competence

OBJECTIVE

To study the efficacy of mitochondrial activator BGP-15 to preserve sperm quality and competence against cellular damage.

DESIGN

Spermatozoa from mice or humans were treated in vitro with BGP-15, and sperm quality markers were assessed. Spermatozoa from young (8-12 weeks old) or reproductively old (>14 months old) mice were treated with BGP-15 for 1 hour and assessed for sperm quality and preimplantation embryo development after in vitro fertilization. The safety of BGP-15 on offspring outcomes was assessed through embryo transfers. In parallel studies, spermatozoa from healthy (not infertile) men were incubated in hydrogen peroxide, to induce oxidative stress, plus increasing doses of BGP-15, and sperm quality was evaluated. Spermatozoa from patients undergoing assisted reproductive technology (ART) treatment were incubated in the optimized dose of BGP-15 for 30 minutes, and sperm quality was assessed.

SUBJECTS

C57BL/6 mice (N = 4-15 per group) for sperm quality and embryo development. CBAF1 mice (n = 6 per group) produced embryos for transfer. Human spermatozoa were from men with no infertility diagnosis (n = 14-20) or men undergoing ART (n = 33) at a local fertility clinic.

EXPOSURE

Mouse spermatozoa were treated with 10-μM BGP-15. Human spermatozoa were treated with BGP-15 at doses from 1 to 100 μM.

MAIN OUTCOME MEASURES

Sperm quality measures (mouse and human) included motility, mitochondrial membrane potential (JC-1 dye), deoxyribonucleic acid (DNA) fragmentation ("HALO" assay), and DNA oxidation (8-oxoguanine immunodetection). Mouse embryo and offspring measures included on-time development after in vitro fertilization, morphokinetic analysis, and blastocyst inner cell mass and trophectoderm cell number, and growth and development from birth to 21 days postnatally.

RESULTS

BGP-15 increased sperm motility and mitochondrial membrane potential and decreased DNA oxidation in old mice. BGP-15 improved on-time development of 2-cell and blastocyst embryos and increased the inner cell mass blastomere number. Embryos from BGP-15-treated mouse spermatozoa produced normal offspring. In human spermatozoa subjected to in vitro oxidative stress, BGP-15 increased motility by 45% and prevented DNA fragmentation (by 45%) and oxidative damage (by 60%). In spermatozoa from men attending a fertility clinic, BGP-15 increased motility by 12% and reduced both DNA oxidation and fragmentation by >20%.

CONCLUSION

BGP-15 protects sperm against cellular damage and has the potential to improve ART outcomes.

Association of abstinence time with semen quality in men who undergoing fertility evaluation: a cross-sectional study from 3052 participants

Objective

Abstinence time has been associated with semen quality, but the results remain controversial.

Methods

This study recruited 3052 men undergoing fertility evaluation. Abstinence time (AT) was categorized as short (0-1 day), WHO-recommended (2-7 days) and long (>7 days). Semen parameters including volume, sperm concentration, progressive motility, total motility, total motility sperm count (TMSC), morphology and DNA fragmentation index were assessed for their association with AT.

Results

Short AT was significantly associated with lower semen volume (P< 0.001), sperm concentration (P= 0.01) and TMSC (P< 0.001), while long AT was significantly associated with higher sperm concentration (P= 0.006), reduced progressive motility (P= 0.005) and total motility (P= 0.02), and higher DFI (P< 0.001). Restricted cubic spline models demonstrated a non-linear relationship between AT and the risk of low semen volume (Pnon-linear < 0.001), sperm concentration (Pnon-linear = 0.039) and TMSC (Pnon-linear < 0.001).

Conclusions

Our findings suggest both short and long AT were significantly associated with lower sperm quality, which indicated the importance of maintaining a recommended AT (2-7days) for semen analysis. Additionally, short abstinence periods may be recommended to maintain optimal sperm DNA integrity.

Sperm DNA Fragmentation and Fertility

Elevated levels of sperm deoxyribonucleic acid (DNA) fragmentation (SDF) have been associated with several adverse reproductive outcomes, including: lower natural and assisted reproductive technology (ART) pregnancy rates, abnormal embryo development, and recurrent pregnancy loss. However, due to conflicting study results, limited high-level evidence, multiple clinically available assays, and variable standard reference ranges, precisely how SDF testing should be applied to the evaluation and treatment of infertile men remains controversial. To better understand SDF and its role in clinical practice, this chapter aims to: (1) review the literature that has made SDF such a controversial topic, (2) discuss newly published evidence contributing to this complex discussion, and (3) outline the most recent practice guidelines currently available.

Abstinence for sperm sample collection and ART outcome: an unsubstantiated myth

PURPOSE OF REVIEW

Semen analysis is a basic component of male evaluation. Reproductive centers typically instruct men to provide a semen specimen based on recommendations from WHO Standard for semen examination. Evidence that these recommendations optimize sperm reproductive capacity is lacking. Existing data to optimize sperm quality with shorter abstinence were reviewed.

RECENT FINDINGS

Several recent studies have reviewed the effects of shorter ejaculatory abstinence of semen quality and assisted reproductive technology (ART) outcomes. Shorter abstinence was defined as 1 h-1 day in one review, and <4 h in the other systematic meta-analysis and review.

SUMMARY

Prior instructions for male patients have not been designed to optimize fertility potential for semen analyses. Optimal sperm quality is obtained by instructing men to have a short abstinence (certainly <1 day, and preferably <4 h) for semen specimens used for in vitro fertilization (assisted reproduction).

Effects of long and short ejaculatory abstinence on sperm parameters: a meta-analysis of randomized-controlled trials

Purpose

This study aimed to investigate the effects of ejaculatory abstinence on sperm parameters.

Methods

This analysis was registered in PROSPERO (CRD42023472124). We performed a search on PubMed using the following text terms: (("sperm parameters" OR "sperm analysis" [Mesh]) AND ("sperm DNA fragmentation" OR "DNA fragmentation" [Mesh]) AND ("sexual abstinence" [Mesh] OR "abstinence")) and an advanced search in Scopus using the terms ("sperm parameters" OR "sperm parameters" OR "DNA fragmentation") AND ("abstinence"). The sperm parameters that were investigated were sperm volume, total sperm motility, progressive sperm motility, sperm concentration, sperm morphology, and sperm DNA fragmentation (SDF). A two-day cut-off as a "short" or "long" abstinence period has been defined.

Results

Thirteen studies published between 2013 and 2022 were included in this meta-analysis. A total of 2,315 patients, ranging from 6 to 836 from each cohort, were enrolled in the study. We showed that longer abstinence time was associated with greater sperm concentration (mean difference [MD]: 8.19; p <0.01), sperm volume (MD: 0.96; p <0.01), and higher SDF (MD: 3.46; p <0.01), but lower progressive sperm motility (MD: -1.83; p <0.01). Otherwise, no statistically significant difference was observed in patients with longer vs. shorter abstinence times regarding total sperm motility (MD: -1.83; p = 0.06). Meta-regression analysis showed that days of abstinence were positively and linearly related to sperm concentration (slope: 3.74; p <0.01) and SDF (slope: 0.65; p = 0.044).

Conclusions

According to our data, short ejaculatory abstinence is associated with better sperm quality. Indeed, a higher percentage of progressive sperm motility and lower levels of SDF have been reported in a short abstinence cohort. In contrast, the long abstinence group reported a higher sperm concentration.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023472124.