Relationship between granulocyte–macrophage colony-stimulating factor, embryo quality, and pregnancy outcomes in women of different ages in fresh transfer cycles: a retrospective study

This study aimed to explore the effects of low-concentration (0.6 ng/mL) granulocyte–macrophage colony-stimulating factor (GM-CSF) supplementation on human embryo quality and pregnancy outcomes in patients with fresh transfer cycles. The data were retrospectively collected from 719 hyperstimulation cycles of 631 patients divided into two groups: GM-CSF supplementation (0.6 ng/mL, n = 399) and control (n = 320). The embryo quality and pregnancy outcomes were compared. GM-CSF addition significantly increased the available embryo rate (52.0 vs. 48.1%, p < .05). In patients >38 years, it significantly enhanced cleavage (99.4 vs. 97.8%, p < .05) and blastocyst formation (45.7 vs. 34.9%, p < .05) rates but not pregnancy outcomes, including clinical pregnancy (power = 0.160) and implantation (power = 0.204) rates. The lack of a statistically significant difference could be related to low study power. These results suggest that low-concentration GM-CSF addition contributes to embryo quality improvement, especially in patients >38 years.IMPACT STATEMENTWhat is already known on this subject? Granulocyte–macrophage colony-stimulating factor (GM-CSF) has a beneficial effect on the development of human embryos in assisted reproductive technology.What do the results of this study add? Adding 0.6 ng/mL GM-CSF significantly increased the available embryo rate. In patients over 38 years of age, it statistically significantly enhanced the cleavage rate (99.4 vs. 97.8%, p < .05) and blastocyst formation rate (45.7 vs. 34.9%, p < .05).What are the implications of these findings for clinical practice and/or further research? GM-CSF benefits embryos with poorer development potential and a randomised clinical trial with a larger sample size should be performed.