Does sperm quality influence oocyte donation treatments? Tambre study on sperm DNA fragmentation at ESHRE

Presenting the first of our four scientific studies at ESHRE 2025

The work, led by Dr. Abraham Zavala, shows that even highly fragmented sperm samples can give rise to euploid embryos when appropriate sperm selection techniques are applied.

Paris is hosting a new edition of the ESHRE congress, the world’s leading event in reproductive medicine, this year 2025, and among the protagonists is a Tambre study that sends a reassuring message to many patients: having a sperm sample with high DNA fragmentation does not necessarily prevent healthy embryos from being obtained if the right techniques are applied.

The study, whose lead author is Dr. Abraham Zavala, gynaecologist at Clinica Tambre, is entitled:
“Sperm Samples with Elevated Double-Strand DNA Fragmentation Demonstrate Similar Fertilization Outcomes to Low Fragmentation When Treated”.
This is a retrospective analysis of 303 oocyte donation cycles with preimplantation genetic diagnosis (PGT-A), performed between 2022 and 2024.

Why is it important to study sperm DNA fragmentation?

In the field of assisted reproduction, sperm quality is a key factor influencing the success of treatments. One of the parameters that causes most concern in men is sperm DNA fragmentation, especially when it affects both strands of the molecule (double stranded). Several studies have suggested that a high level of this type of damage may impair fertilisation, reduce blastocyst formation and increase the likelihood of chromosomal alterations.

However, until now, the available clinical data was limited, and many patients with this condition faced uncertainty or even recommendations to resort to sperm donation.

“The aim of our study was to test whether elevated levels of double-stranded DNA fragmentation really affect embryo outcomes, especially in a controlled setting such as PGT-A ovodonation“, explains Dr Zavala.

Study design: 303 cycles with egg donation and PGD

Tambre’s team reviewed 303 in vitro fertilisation treatments with egg donation, all of them with preimplantation genetic diagnosis to select chromosomally normal embryos. The spermatozoa from each sample were analysed using the Comet assay to determine the percentage of double-stranded DNA fragmentation. Based on the result, samples were grouped into three categories: <60%, 60-69% and ≥70%.

To optimise sperm selection, different techniques were applied depending on the level of fragmentation: the classic swim-up method, the Zymot-ICSI or CHIP-Fertile microfluidic chip or the SpermSlow selection medium, mainly used when fragmentation exceeded 80% or in the case of frozen samples.

All fertilisations were performed by ICSI (intracytoplasmic sperm injection), and embryos were cultured until blastocyst (day 5-6 of embryo development), at which time they were biopsied for chromosomal endowment analysis by next-generation sequencing (NGS).

Reassuring results: no significant differences

Despite the differences in the level of fragmentation, the results were very similar between the three groups:

• The mean number of mature oocytes (MII) and fertilised embryos (2PN) did not vary significantly.
• The rate of blastocyst formation was comparable between groups.
• The number of euploid embryos (with the correct number of chromosomes) also showed no statistically significant differences.

For example, the mean number of euploid embryos was 3.03 in the group with <60% fragmentation, 2.85 in the intermediate group (60-69%) and 3.28 in the group with ≥70%. There were also no significant differences in the rates of aneuploidy (embryos with chromosomal alterations) or in the proportion of mosaic embryos.

“The most important finding is that, when appropriate methods are used to select spermatozoa, even those with high fragmentation can give rise to viable and chromosomally normal embryos,” Dr Zavala emphasises. “This brings peace of mind to both professionals and couples facing this problem“.

Clinical implications: precision and personalisation in sperm selection

One of the strengths of this study is that it was conducted in a real clinical context, with a homogeneous methodology and applying advanced sperm selection techniques. Specifically, the method was adapted to each case, using technologies such as Zymot-ICSI (CHIP-Fertile), which uses microfluidics to select the spermatozoa with the best integrity, or SpermSlow, which helps to identify those with the best morphology and motility.

This personalised approach is essential, especially when working with compromised samples. In addition, the fact that all eggs came from young donors eliminated the female age factor, which reinforces the validity of the results.

Limitations and considerations: results apply only to oocyte donation cycles

Although the results are promising, the authors stress that this study focuses exclusively on cycles with donor oocytes. In other words, it cannot be directly extrapolated to treatments with autologous oocytes, where age and oocyte quality may be more limiting factors.

Furthermore, as this is a retrospective analysis of a single centre, the existence of uncontrolled variables influencing the results cannot be ruled out. For this reason, the Tambre team believes that prospective studies with a larger number of patients and different clinical profiles are needed.

A step forward in precision reproductive medicine

This study is part of Tambre’s commitment to personalised reproductive medicine based on scientific evidence. Thanks to research such as this, progress is being made in understanding male factors that until now were difficult to address clinically.

“Many men with alterations in sperm DNA fragmentation feel great pressure or fear of treatment failure. Our work shows that, with the right technology, we can overcome these barriers and offer real and effective options,” concludes Dr Zavala.

Benefits for patients: science for trust and confidence

The findings presented at ESHRE 2025 have a clear impact on patient care. On the one hand, they help reduce the anxiety of many couples who receive a diagnosis of high fragmentation. On the other hand, they reinforce the importance of using centres with specialised equipment and advanced laboratory techniques.

Studies like this also allow professionals to make decisions based on data rather than assumptions, which improves counselling, treatment planning and, ultimately, the likelihood of success.