Low Sperm Count and ICSI Success: What a Donor-Egg Study Found

By Seungjoo Lee

Does total motile sperm count predict ICSI success? A retrospective study of 862 couples receiving donor-oocyte ICSI at 15 Spanish fertility centers found no independent association with embryo quality or reproductive outcomes after adjustment. A low sperm count alone did not reliably predict cumulative live birth in this setting.

When a man preparing for IVF is told his sperm count is low, concern often extends to embryos: will fertilization fail, will embryo quality be poor, or will pregnancy be less likely? In ICSI, where a single sperm is injected directly into an oocyte, the meaning of the overall count may be less straightforward.

The study was published on September 26, 2026, in the Journal of Assisted Reproduction and Genetics. Researchers reported that total motile sperm count (TMSC) did not independently predict embryo quality or treatment success in the donor-oocyte cycles studied.

Using donor eggs to reduce the influence of oocyte factors

Female age and oocyte quality strongly influence IVF outcomes. As age increases, the risk of oocyte chromosomal abnormalities rises, making sperm-related and egg-related effects difficult to separate in general patient populations.

To reduce this influence, investigators examined donor-oocyte ICSI treatment in 862 couples across 15 centers in Spain between 2008 and 2023.

TMSC combines semen volume, sperm concentration and motility to estimate the total number of moving sperm in an ejaculate. It is different from concentration alone.

The team assessed TMSC before processing and after sperm selection. Patients were divided into five groups ranging from fewer than one million to more than 20 million motile sperm.

They compared fertilization, embryo quality and pregnancy outcomes, including cumulative live birth rate (CLBR), which considers the overall chance of live birth from treatment using embryos obtained from one oocyte retrieval.

Initial differences disappeared after adjustment

Unadjusted comparisons showed some differences in fertilization and cumulative live birth according to fresh, pre-processing TMSC.

After adjustment for factors including male age, body mass index, donor age, sperm-selection method and the WHO semen criteria used, those associations were no longer statistically significant.

Neither fresh nor post-selection TMSC consistently predicted fertilization, embryo quality, pregnancy outcomes or CLBR. A smaller total number of moving sperm therefore did not, by itself, establish poorer embryos or a lower probability of live birth after ICSI in this population.

Why ICSI changes the significance of sperm numbers

In conventional IVF, many sperm are placed around an oocyte and a sperm must penetrate it. Count and motility can therefore be important to fertilization.

In ICSI, an embryologist selects a sperm under the microscope and injects it into the oocyte’s cytoplasm using a fine needle. When usable sperm can be obtained, the overall count may be less decisive than in conventional insemination.

This does not mean sperm quality is unimportant. TMSC primarily reflects count and movement; it does not measure every aspect of sperm DNA damage, chromosomal abnormalities or functional problems that could affect fertilization and early embryo development.

The finding is therefore that low TMSC alone is insufficient to predict embryo quality and ICSI success, not that sperm biology no longer matters.

A low count is not a complete prognosis

The investigators concluded that neither fresh nor post-selection TMSC was independently associated with reproductive outcomes after adjustment in donor-oocyte ICSI.

A low concentration or motility result should not automatically be translated into a poor chance of obtaining a good embryo, achieving pregnancy or having a baby.

Important limitations remain. This was a retrospective observational analysis of records collected from 2008–2023, and it included only donor-oocyte cycles. Its findings cannot be applied unchanged to all IVF or ICSI patients using their own eggs.

Even so, the analysis of 862 couples is informative because it reduces some of the variation arising from oocyte factors. When usable sperm are available for ICSI, prognosis should consider both partners’ ages, oocyte condition, sperm function, fertilization and embryo development rather than a single count.

Study source and interpretation

Andrea Crafa, Rossella Cannarella and colleagues, Predictive value of fresh and post-selection total motile sperm count on embryo quality and success rate of intracytoplasmic sperm injection in cycles with donated oocytes: a retrospective multi-center study, Journal of Assisted Reproduction and Genetics, September 26, 2026. Retrospective study of 862 couples undergoing donor-oocyte ICSI at 15 Spanish fertility centers. DOI: 10.1007/s10815-026-04026-6; PMID 42799966.

This article presents research findings. Individual causes of infertility and treatment choices require clinical assessment of semen, ovarian function, age and prior treatment.

Illustration note: the translated sperm-count chart reproduces the original publisher’s illustrative concentration categories. Concentration in sperm/mL is not the same measure as TMSC; neither the chart nor a single count can diagnose infertility or determine treatment.