P-083 Short ejaculatory abstinence time of 2 hours results in higher pregnancy outcomes compared to the recommended abstinence period of 2-7 days
Authors: Wouters K , Mateizel I , Van Asbroeck J , Schoemans C , Abraham M , Krunic M , Tournaye H , Vloeberghs V , De Munck N 
Published: July 2024

Abstract

Study question
What is the impact of a short abstinence (2h) compared to the recommended (2-7 days) ejaculatory abstinence time on embryo utilization rate and pregnancy outcome?

Summary answer
A short abstinence of 2 hours results in similar embryo utilization rates, but in reduced sperm DNA fragmentation and higher pregnancy rates.

What is known already
Semen parameters exhibit variability among and within individuals, and ejaculatory abstinence time (EA) is a known factor contributing to intra-individual variation. Despite the challenge of providing a specific recommendation for the optimal timeframe, recent studies suggested that a shorter abstinence is likely to decrease DNA fragmentation levels in semen and improve pregnancy and live birth rates following assisted reproductive technology. At present, ESHRE recommends a more limited range than the WHO manual, advising an ejaculatory abstinence of 3 to 4 days.

Study design, size, duration
This prospective proof-of-concept sibling oocyte study (n = 100 cycles), conducted between January 2018 and June 2023, required two sperm samples per patient. The initial sperm sample was produced on the day of oocyte retrieval following the requested abstinence period of 2-7 days. The second sperm sample was collected 2 hours later. Sibling oocytes were randomly allocated to injection with the first or second sample. Sibling oocytes of each patient were cultured under the same conditions.

Participants/materials, setting, methods
Inclusion criteria were ≥ 6 mature oocytes (MII), fresh ejaculates with concentration &gt;1x106/ml, ICSI with subsequent blastocyst culture. Endpoints were pregnancy outcome, fertilization, blastocyst development, utilization rate, sperm concentration/motility and DNA fragmentation index (DFI) measured by TUNEL. Statistical analysis was done taking into account female age and clustering. A total of 104 couples consented to provide two samples on the day of oocyte retrieval and were enrolled.

Main results and the role of chance
Average abstinence periods of 98:48h±20:01 vs 02:05h±00:18 were observed. Sperm concentration (x106/ml), progressive forward motility and DFI, were 46.53±39.6 vs 37.0±37.1 (p &lt; 0.001), 52.14%±20.1 vs 49.79%±20.4 (p = 0.152) and 6.76%±7.0 vs 5.37%±7.2 (p = 0.024), respectively.
Of the 1282 collected oocytes, 634 were injected with the first sperm sample and 648 with the ‘2h EA sample’. Fertilization rates per MII (79.3% vs 80.7%, p = 0.154) and good-quality day 3 embryos (76.7% vs 77.6%, p = 0.276) were similar between both groups.
From the 93 patients with blastocyst culture (with average female age of 33.9±5.0 years; average male age of 36.4±6.6 years), 1173 oocytes were stratified for injection: 580 (first sample) and 593 (second sample), respectively. Fertilization rates (81.4% vs 82.3%, p = 0.074) and good-quality day 5 blastocysts (46.2% vs 49.5%, p = 0.534) did not differ between the groups. Utilization rate per inseminated (30.5% vs 35.8%, p = 0.126) or fertilized (37.5% vs 43.4%, p = 0.153) oocyte was similar between the groups.
Single fresh and frozen embryo transfers were compared between embryos generated after the requested (2-7 days; n = 91) and short (2h; n = 94) abstinence. Pregnancy rate was significantly higher after short abstinence: 49.5% (45/91) vs 62.8% (59/94); p = 0.01. Ongoing pregnancy rate was 31.9% (29/91) and 40.4% (38/94); p = 0.10.

Limitations, reasons for caution
This is a prospective proof-of-concept study, not powered to detect differences in utilization and pregnancy outcomes. Not all patient are capable of producing two sperm samples within 2 hours from each other.

Wider implications of the findings
The results indicate a significant, yet not relevant difference in DNA fragmentation index (DFI) but a relevant difference in pregnancy rate between the two groups. If increased live birth rates are obtained after short abstinence, recommendations concerning EA might need adaptation.

Trial registration number
NCT03323892