Time intervals between semen production, initiation of analysis, and IUI significantly influence clinical pregnancies and live births

Swim-up versus density gradients for sperm preparation in infertile couples undergoing intrauterine insemination: a randomized clinical trial

STUDY QUESTION

What is the effectiveness of swim-up (SU) and density gradients (DG) for sperm preparation in infertile couples undergoing IUI?

SUMMARY ANSWER

In infertile couples undergoing IUI, SU and DG did not result in statistically significant different live birth rates.

WHAT IS KNOWN ALREADY

SU and DG are the two most commonly used techniques for sperm preparation in infertile couples undergoing IUI. In the latest Cochrane review, given the very low quality of available data, the authors were uncertain whether there was a difference in clinical pregnancy rates between the two techniques. Furthermore, live birth rate was not reported in any trial.

STUDY DESIGN, SIZE, DURATION

This open-label, two-centre, randomized clinical trial was conducted at two IVF centres in Vietnam. A sample size of 912 couples was needed to demonstrate a 5% difference between SU and DG (power 0.80, two-sided alpha 5%, loss to follow-up, and cross-over rate 10%). Randomization was performed using a computer-generated random list, with a variable block size of 2, 4, or 6. Assignment to treatment allocation was done via a web portal.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Eligible couples included those who were ≥18 years of age, where the husbands' sperm concentration, progressive motility (PM) rate, and total PM sperm count before sperm preparation were ≥5 × 106/ml, ≥32%, and >5 × 106 (according to the WHO 2010 criteria), respectively. Couples using frozen semen, or couples where the husband's semen was hyperviscous, were not included. On the day of IUI, participants were randomized (1:1 ratio) to undergo either SU or DG. Sperm preparation was performed within 1 h after ejaculation. IUI was performed once at 36-40 h after hCG trigger. Primary outcome was live birth after the first IUI cycle.

MAIN RESULTS AND THE ROLE OF CHANCE

Between 7 August 2020 and 29 October 2022, we randomized 456 couples to SU and 456 couples to DG. Live birth after the first IUI cycle occurred in 55 (12.1%) couples in the SU group and 71 (15.7%) couples in the DG group (relative risk 0.77; 95% CI 0.56 to 1.07). There were no statistically significant differences between the two groups in terms of other pregnancy outcomes as well as obstetrics and perinatal outcomes.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of the study was its open-label design, due to the nature of the interventions.

WIDER IMPLICATIONS OF THE FINDINGS

In infertile couples undergoing IUI, SU and DG can both be used for sperm preparation. The decision on which to use might depend more on practical factors such as processing time and how easy it is to standardize the method.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by My Duc Hospital, Ho Chi Minh City, Vietnam. B.W.M. is supported by a NHMRC Investigator grant (GNT1176437), reports consultancy, travel support, and research funding from Merck and consultancy for Organon and Norgine, and holds stock from ObsEva. L.N.V. has received grant, speaker, and conference fees from Merck Sharpe and Dohme, and grant, speaker, conference, and scientific board fees from Ferring. T.M.H. has received grant, speaker, and conference fees from Merck Sharpe and Dohme, and grant, speaker, conference, and scientific board fees from Ferring.

TRIAL REGISTRATION NUMBER

NCT04477356.

TRIAL REGISTRATION DATE

6 July 2020.

DATE OF FIRST PATIENT’S ENROLMENT

10 August 2020.

Ejaculate Adjustment in Response to Sperm Competition Risk in Humans

Previous research suggests that human males, like males of many mammalian and avian species, adjust their ejaculate quality in accordance with sperm competition risk. Men who spend less time with their regular female partner since the couple's last copulation produce ejaculates with more sperm at the couple's next copulation (Baker & Bellis, 1993). We conducted a conceptual replication of this research to investigate whether sperm competition risk predicts ejaculate adjustment in human males using additional measures of sperm competition risk (e.g., perceptions of partner infidelity, presence of potential sexual rivals) and updated laser-optic semen analysis technology. We collected data from 34 heterosexual couples (age range 18-32 years) from a university population who completed self-report surveys on their relationship dynamics and provided six ejaculate samples (three copulatory and three masturbatory) across a 45-day period. Time spent together since the couple's last copulation was not significantly associated with ejaculate quality. However, sperm concentration for copulatory ejaculates was higher for men who perceived more potential sexual rivals. Discussion situates the current results within the literature on human sperm competition and suggests several directions for future research.

Sperm DNA Fragmentation after Cryopreservation and Sperm Selection Has No Implications for Clinical Pregnancies and Live Births after Intrauterine Insemination with Donor Sperm

Intrauterine insemination with donor sperm (IUI-D) requires multiple in vitro manipulations such as sperm selection and cryopreservation during which spermatozoa may be exposed to oxidative stress (OS) and other insults that may produce potential damage including sperm DNA fragmentation (SDF). High levels of SDF, referring to damage or breaks in the genetic material of sperm cells, are linked to an increased risk of reproductive failure. This retrospective, observational study set out to evaluate whether SDF assessment could predict clinical outcome in an IUI-D program, where sperm donors are selected on strict conventional semen parameters. A total of 18 donors and 106 recipients were matched for IUI-D. Out of 429 cycles, 100 (23.3%) resulted in clinical pregnancy. We counted 78 live births (18.2% of cycles), while 20 pregnancies ended in miscarriage (4.7% of cycles), 1 in extra-uterine pregnancy and 1 in stillbirth. Female age significantly influenced clinical pregnancy and miscarriage rates. SDF increased after cryopreservation (26.3 ± 14.5%; p < 0.001) and more so after post-thaw density gradient (34.9 ± 22.1%; p = 0.04) without affecting clinical pregnancy (OR [95% CI] 1.01 [0.99; 1.02]; p = 0.27), live birth (1.00 [0.99; 1.02]; p = 0.72) and miscarriage rates (1.02 [1.00; 1.05]; p = 0.08). The implications of our findings extend to a better selection of sperm donors and a better sperm preparation technique tailored to the donor semen's properties in order to maximize the chances of a favorable treatment outcome.

A short versus a long time interval between semen collection and intrauterine insemination: a randomized controlled clinical trial

STUDY QUESTION

Does a short interval (i.e. ≤90 min), compared to a long interval (i.e. ≥180 min), between semen collection and intrauterine insemination (IUI) increase the cumulative chance of an ongoing pregnancy after six IUI cycles?

SUMMARY ANSWER

A long interval between semen collection and IUI resulted in a borderline significant improvement in cumulative ongoing pregnancies and a statistically significant shorter time to pregnancy.

WHAT IS KNOWN ALREADY

Retrospective studies assessing the effect of the time interval between semen collection and IUI on pregnancy outcomes have shown inconclusive results. Some studies have indicated a beneficial effect of a short interval between semen collection and IUI on IUI outcomes, while others have not found any differences. To date, no prospective trials have been published on this subject.

STUDY DESIGN, SIZE, DURATION

The study was performed as a non-blinded, single-center RCT with 297 couples undergoing IUI treatment in a natural or stimulated cycle. The study was conducted between February 2012 and December 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Couples with unexplained or mild male subfertility and an indication for IUI were randomly assigned for up to six IUI cycles into either the control group (long interval, i.e. 180 min or more between semen collection and insemination) or the study group (short interval, i.e. insemination as soon as possible after semen processing and within 90 min of semen collection). The study was carried out in an academic hospital-based IVF center in the Netherlands. The primary endpoint of the study was ongoing pregnancy rate per couple, defined as a viable intrauterine pregnancy at 10 weeks after insemination.

MAIN RESULTS AND THE ROLE OF CHANCE

In the short interval group, 142 couples were analyzed versus 138 couples in the long interval group. In the intention-to-treat (ITT) analysis, the cumulative ongoing pregnancy rate was significantly higher in the long interval group (71/138; 51.4%) compared to that in the short interval group (56/142; 39.4%; relative risks 0.77; 95% CI 0.59-0.99; P = 0.044). The time to pregnancy was significantly shorter in the long interval group (log-rank test, P = 0.012). A Cox regression analysis showed similar results (adjusted hazard ratio 1.528, 95% CI 1.074-2.174, P = 0.019).

LIMITATIONS, REASONS FOR CAUTION

Limitations of our study are the non-blinded design, the long inclusion and follow-up period of nearly seven years and the large number of protocol violations, especially because they predominantly occurred in the short interval group. The non-significant results in the per-protocol (PP) analyses and the weaknesses of the study should be taken into account in the assessment of the borderline significance of the results in the ITT analyses.

WIDER IMPLICATIONS OF THE FINDINGS

Because it is not necessary to perform the IUI immediately after semen processing, there can be more time available to choose the optimum work-flow and clinic occupancy. Clinics and laboratories should find their optimal timing of insemination, considering the time between human chorionic gonadotropin injection and insemination in relation to the sperm preparation techniques used as well as the storage time and conditions until insemination.

STUDY FUNDING/COMPETING INTEREST(S)

There were no external funding and no competing interests to declare.

TRIAL REGISTRATION NUMBER

Dutch trial registry, trial registration number NTR3144.

TRIAL REGISTRATION DATE

14 November 2011.

DATE OF FIRST PATIENT’S ENROLLMENT

5 February 2012.

Variability in Sperm DNA Fragmentation in Men with Mild/Unexplained Subfertility in a Prospective Longitudinal Intrauterine Insemination Trial

The biological variability of semen and sperm DNA fragmentation (SDF) parameters in a longitudinal intrauterine insemination (IUI) trial over multiple IUI cycles was investigated. A TUNEL assay was used for SDF testing, both before and after density gradient centrifugation. A significant age effect was observed: while semen parameters deteriorated with advancing age, on average, higher SDF values were observed for older males. There was quite some variability observed for both semen and SDF variables. Using fertile threshold values, three patient categories were distinguished: those with a high SDF in all samples, those with low SDF in all samples and those who fluctuated between high and low during the whole IUI trial. Density gradient centrifugation increases SDF. However, the three patient categories react differently after semen processing. A large percentage of those with high SDF retain their high SDF even after gradient centrifugation. The SDF fluctuaters react with a high SDF after gradient centrifugation. The low SDF category, on the contrary, distributes itself evenly between the three categories after gradient centrifugation. SDF testing after semen processing might be indispensable for therapeutic purposes, probably influencing medical decision-making. In order to isolate fluctuaters, a second SDF testing might be advocated in certain cases. SDF after semen processing is indispensable for therapeutic management.

Extend the Survival of Human Sperm In Vitro in Non-Freezing Conditions: Damage Mechanisms, Preservation Technologies, and Clinical Applications

Preservation of human spermatozoa in vitro at normothermia or hypothermia maintaining their functions and fertility for several days plays a significant role in reproductive biology and medicine. However, it is well known that human spermatozoa left in vitro deteriorate over time irreversibly as the consequence of various stresses such as the change of osmolarity, energy deficiency, and oxidative damage, leading to substantial limitations including the need for semen examinations, fertility preservation, and assisted reproductive technology. These problems may be addressed with the aid of non-freezing storage techniques. The main and most effective preservation strategies are the partial or total replacement of seminal plasma with culture medium, named as extenders, and temperature-induced metabolic restriction. Semen extenders consist of buffers, osmolytes, and antioxidants, etc. to protect spermatozoa against the above-mentioned adverse factors. Extended preservation of human spermatozoa in vitro has a negative effect on sperm parameters, whereas its effect on ART outcomes remains inconsistent. The storage duration, temperature, and pre-treatment of semen should be determined according to the aims of preservation. Advanced techniques such as nanotechnology and omics have been introduced and show great potential in the lifespan extension of human sperm. It is certain that more patients will benefit from it in the near future. This review provided an overview of the current knowledge and prospects of prolonged non-freezing storage of human sperm in vitro.