Researchers in a 2025 meta-analysis combined the results of 21 studies and found that microfluidic sperm selection improved embryo quality and slightly improved fertilization rates, but it didn’t significantly improve euploid, pregnancy, or live birth rates.
Sperm processing is an important step before IVF or ICSI. The most common method, density gradient centrifugation, separates healthy sperm by spinning the sample. Another option is microfluidics, like the Zymot device, which allows the most motile sperm to swim through tiny channels without centrifugation.
Microfluidic devices have been shown to reduce sperm DNA fragmentation, raising the possibility that they could improve embryo development and pregnancy outcomes.
However, studies comparing microfluidic sperm selection with conventional sperm preparation have reported mixed results. Thanapongpibul et al. (2025) combined the results of 21 studies to better understand whether Zymot and other microfluidic devices improve IVF outcomes compared to conventional methods.
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Table of Contents
Study details
- Study design: Systematic review and meta-analysis of 21 studies, published between 2019 and 2024, comparing microfluidic sperm selection (mainly Zymot) with conventional sperm preparation (density gradient centrifugation or swim-up) for ICSI. There were 12 randomized trials and 9 retrospective studies included.
- Risk of bias: The authors judged most studies to have a low risk of bias, with 15 rated as low risk and 6 as moderate risk. No studies were considered to have a high overall risk of bias.
- Participants: Studies included couples undergoing ICSI for a variety of infertility diagnoses, including unexplained infertility, male factor infertility, recurrent ART failure, previous low fertilization, and unselected IVF patients.
Zymot sperm selection improved some IVF lab outcomes
Across the 21 included studies, microfluidic sperm selection was associated with modest improvements in several laboratory outcomes compared with conventional sperm preparation methods.
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Fertilization. Based on 6 studies, the odds of fertilization were 4% higher with microfluidic sperm selection than with conventional sperm preparation (odds ratio [95% CI]: 1.04 [1.00–1.07], I2= 30.6%). Some notes on interpreting this below:
- This means the odds of fertilization were 4% higher with microfluidic sperm selection. This is different from saying the fertilization rate was 4% higher. A 4% increase in the odds usually corresponds to a much smaller increase in the actual fertilization rate. For example, if the fertilization rate was 70% with conventional sperm preparation, a 4% increase in the odds would increase the fertilization rate to about 70.8%, not 74%.
- This was a borderline result because the confidence interval started at 1.00, which represents no difference between the groups. This suggests that any benefit, if it truly exists, is likely to be small.
- High quality embryos (per mature egg). Based on 5 studies, the odds of getting a high quality embryo was 44% higher with microfluidic sperm selection (odds ratio [95% CI]: 1.44 [1.30–1.60], I2= 59.0%). For example, if 30% of mature eggs developed into high quality embryos with conventional sperm preparation, a 44% increase in the odds would correspond to about 38%.
- Euploid embryos: Based on 3 studies, there was no statistically significant difference in euploid rates (odds ratio [95% CI]: 1.20 [0.92–1.58]).
Pregnancy outcomes were similar overall
Although microfluidic sperm selection improved some laboratory outcomes, this didn’t translate into better pregnancy outcomes.
- Clinical pregnancy: Based on 14 studies, there was no statistically significant difference in pregnancy rates (odds ratio [95% CI]: 1.09 [0.94–1.25], I2= 53.2%).
- Live birth: Based on 8 studies, there was no statistically significant difference in live birth rates (odds ratio [95% CI]: 1.27 [0.99–1.62], I2= 48.6%).
Conclusions
Researchers combined the results of 21 studies and found that Zymot and other microfluidic devices improved embryo quality and slightly improved fertilization rates. However, it did not significantly improve euploidy, overall pregnancy rates, or live birth rates.
Researchers also looked at whether some groups of patients benefited more than others. While some subgroup analyses suggested possible benefits in patients with male factor infertility, unexplained infertility, or previous low fertilization, these results were based on fewer studies and are generally considered less reliable than the overall results.
These results are generally consistent with a 2023 meta-analysis by Aderaldo et al. (2023). Like this newer meta-analysis, it found a small improvement in fertilization rates and a larger improvement in high-quality blastocyst rates, but no significant differences in pregnancy rates.
An important limitation is that the included studies generally were not designed to evaluate patients with high sperm DNA fragmentation (SDF). Because microfluidic sperm selection has consistently been shown to reduce SDF (Iranzo et al. 2025), patients with high SDF may benefit more from this technology than the general IVF population. However, since many clinics use microfluidic sperm selection regardless of SDF levels, this meta-analysis provides a useful estimate of its overall effects in the general IVF population.
Another limitation is that the meta-analysis included both randomized and retrospective studies. Because retrospective studies are generally more prone to bias, this may have affected some of the results.
Want to read more about Zymot and sperm DNA fragmentation?
In a 2025 study, the sperm selection device Zymot modestly improved blastocyst development compared with conventional sperm processing method (density gradient centrifugation) in donor egg cycles using frozen sperm, though fertilization rates were similar. Read more.
A 2024 randomized controlled trial (RCT) found that Zymot-selected sperm didn’t improve embryo euploidy rates, but increased fertilization rates. An important limitation of this study is that it was done in the general IVF population and not in individuals with high sperm DNA fragmentation. Read more.
A 2025 review found that sperm DNA fragmentation testing provides useful insight into male infertility and may help in select cases, but inconsistent evidence, lack of test standardization, and variable results limit its routine use in fertility care. Read more.
Reference
Topraggaleh, Tohid Rezaei, Azizi, Hosein, Fattahi, Amir, Dadkhah, Ehsan, Niknafs, Behrooz, Comparison of ICSI Outcomes Between Microfluidic and Conventional Sperm Selection Methods: A Systematic Review and Meta-Analysis, Andrologia, 2025, 9210663, 13 pages, 2025. https://doi.org/10.1155/and/9210663
About Embryoman
Embryoman (Sean Lauber) is a former embryologist and the founder of Remembryo, an IVF research and fertility education website. After working in an IVF lab in the US, he returned to Canada and now focuses on making fertility research more accessible. He holds a Master’s in Immunology and launched Remembryo in 2018 to help patients and professionals make sense of IVF research. Sean shares weekly study updates on Facebook, Instagram, and Reddit regularly. He also answers questions on Reddit or in his private Facebook group.
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