Cumulative Live Birth Rates Differ by Culture Medium: 41.0% vs. 34.5% Multicenter Randomized Controlled Trial Across 5 Dutch Fertility Centers Analyzes 1,013 IVF Patients CSCM Group 41.0% vs. G5 Group 34.5%… Disparities Also Seen in Fertilization and Usable Embryo Rates Adjusted Analysis at p = 0.057… Premature to Conclude That Culture Medium Conclusively Drives Up Childbirth Rates
The success or failure of an In Vitro Fertilization (IVF) cycle may not depend solely on maternal age, sperm quality, and endometrial receptivity. Emerging research reveals that the culture medium in which an embryo develops for several days post-fertilization may also exert a meaningful influence on clinical outcomes.
In a multicenter randomized controlled trial (RCT) conducted by Dutch researchers and published in Supplement 1 of the international journal Human Reproduction (presented as an abstract at ESHRE 2026), comparing two commercial culture media demonstrated a 6.5 percentage point difference in cumulative live birth rates (41.0% vs. 34.5%).
Study Design and Key Findings
Between February 2016 and January 2022, the research team randomly assigned 1,016 couples undergoing IVF across five fertility centers in the Netherlands to either the CSCM culture medium or the G5 culture medium. The final analysis evaluated 1,013 patients.
Randomization was stratified by female age, fertilization method, and study center, with both patients and treating physicians blinded to the allocated medium.
The clinical results were noteworthy:
- CSCM Group: Among 505 patients, 207 achieved a live birth, resulting in a cumulative live birth rate of 41.0%.
- G5 Group: Among 508 patients, 175 achieved a live birth, recording a 34.5% rate.
A major strength of this study is that it evaluated the cumulative live birth rate—incorporating all live births resulting from both fresh and frozen-thawed embryo transfers originating from a single oocyte retrieval cycle—rather than limiting the comparison to the initial fresh transfer alone.
Similar trends emerged during early embryonic development:
- Fertilization rate: 68.2% for CSCM vs. 65.7% for G5.
- Usable embryo rate (transferred or cryopreserved): 40.7% for CSCM vs. 38.2% for G5.
- Clinical pregnancy and ongoing pregnancy rates likewise consistently favored the CSCM cohort.
Statistical Nuance and Study Limitations
Despite these findings, it remains difficult to conclude immediately that “CSCM is definitively superior to G5” or that “switching culture media directly boosts childbirth rates.”
In the multivariate analysis adjusting for age, fertilization method, and treatment center:
- The adjusted odds ratio (OR) for cumulative live birth in the CSCM group was 1.29 (95% CI: 0.99–1.66).
- The p-value was p = 0.057, slightly exceeding the conventional statistical significance threshold of 0.05.
While a 6.5 percentage point gap appears clinically meaningful, statistical uncertainty remains regarding whether this divergence can be attributed solely to the culture medium.
Sample size was another notable limitation. The researchers initially calculated that 1,980 participants were necessary to detect a 6% difference in cumulative live birth rates; however, only 1,016 patients were randomized before the study concluded early. This reduced the statistical power of the trial. Furthermore, the findings are restricted to the two evaluated media (CSCM and G5) and cannot be generalized across other commercial formulations.
Broadening the Scope of IVF Variables
Nevertheless, the questions raised by this trial carry significant weight.
In IVF, culture medium is not merely a passive liquid used to store embryos; it is the dynamic microenvironment with which the zygote directly interacts as it develops into a blastocyst. While reproductive medicine has historically emphasized maternal age, ovarian reserve, sperm parameters, and embryo grading, this study indicates that the laboratory culture environment may also link directly to cumulative treatment outcomes.
The most precise interpretation of these findings is not that “a specific culture medium boosted birth rates,” but rather that “a clinically meaningful difference in cumulative live birth rates was observed between two culture media.”
What nutrients an embryo receives and what environment it inhabits during those critical days between fertilization and transfer represent crucial factors. This study brings the often invisible differences within the IVF laboratory back to the forefront as an essential variable in understanding IVF success.
※ This article was synthesized based on the results of a multicenter randomized controlled trial (RCT) conducted by Dutch researchers and published in Supplement 1 of the international journal Human Reproduction. It does not replace individual medical diagnosis or treatment, and actual clinical decisions must be made in consultation with a qualified specialist.
※ Source: M. Laverde et al., “Effect of embryo culture medium on live birth and perinatal outcomes after IVF: a multicenter RCT,” Human Reproduction, July 2026.
※ The images used in this article were generated using generative AI (ChatGPT, OpenAI) as visual references to aid understanding and do not depict real individuals.