Short ejaculatory abstinence time is associated with higher pregnancy and live birth rates and improved DNA fragmentation index (DFI): A Systematic Review

Abstract Study question Does short ejaculatory abstinence time (EA) improve DNA fragmentation and reproductive outcomes compared with long EA following assisted reproductive technology (ART)? Summary answer Shorter EA is associated with improved pregnancy and live birth rates following ART and lower DFI compared with longer EA at different cut-off points. What is known already When spermatozoa pass the epididymal tract, they are exposed to reactive oxygen species (ROS). ROS is known to cause DNA fragmentation. Testicular sperm has a lower DNA fragmentation when compared to ejaculated sperm, which indicates that DNA fragmentation is increased during the transition and storage in the epididymal duct. There are studies that suggest that a high DFI is associated with poor pregnancy and live birth rates following ART. WHO recommends 2-7 days of EA prior to semen collection; however, several recent studies have reported a correlation between shorter EA and improved reproductive outcomes and DFI. Study design, size, duration A systematic review was conducted according to the PRISMA guidelines and registered in PROSPERO (CRD42022379039). The electronic databases PubMed, Embase and Cochrane were searched for eligible studies by a research librarian in April 2022. Additional articles were manually retrieved after reviewing the reference lists from relevant publications. Participants/materials, setting, methods Two authors independently screened studies based on the eligibility criteria; studies including men referred to fertility treatment undergoing short and long EA reporting data on pregnancy rate, live birth rate and DFI. Study demographics, population characteristics and data on study outcomes including statistical analyses were extracted. Risk of bias in each study was evaluated according to The Scottish Intercollegiate Guidelines Network (SIGN). Any disagreements were resolved by a third author. Main results and the role of chance Out of 1237 studies initially identified, 24 of them met eligibility criteria and were included in the review with a total of 14.173 cases. The studies included in this review were conducted in Asia, North and South America and Europe. The cause of referral to fertility treatment includes both male, female, mixed and unexplained infertility. The EA varied from less than a one hour to as long as 15-20 days. Nine of the 13 studies investigated the influence of varying EA on pregnancy rate, found a significantly higher pregnancy rate with short EA compared with long EA, five with EA as short as one day or less. Three studies evaluated live birth rates and found a significantly higher live birth rate when comparing short EA with long EA. Eleven of the 15 studies that reported DFI found significantly lower DFI with short EA compared with long EA. EA of one day or less were associated with the lowest rates of DFI in the studies. In general, pregnancy rate, live birth rate and DNA fragmentation are likely to be improved with short EA compared to long EA. Limitations, reasons for caution Many of the included studies used different EA intervals, leading to heterogenous data, and therefore, only allowed limited conclusion to be formulated regarding the ideal timeframe of EA. Four studies scored poorly in SIGN methodology checklist due to confounding and population size, suggesting their findings to be treated with caution. Wider implications of the findings Even though it is difficult to make a clear recommendation on the ideal timeframe for EA because of the heterogenous abstinence periods, this review suggest decreasing the EA limits of 2-7 days as recommended by WHO to improve pregnancy rate and decrease DNA fragmentation in semen, followed by ART. Trial registration number not applicable