The use of GM-CSF increases the probability of pregnancy by 47% and halves the miscarriage rate, even in patients with a history of implantation failure. This is the main conclusion of a study led by Dr Llanos Medrano, National Coordinator of Laboratories at the IVF-Life group, which will be presented at the upcoming Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE), to be held in Paris from 29 June to 2 July.
The study, conducted on 575 cryotransfers at the IVF-Life clinic in Alicante, analyses the impact of using a special culture medium enriched with GM-CSF (granulocyte-macrophage colony-stimulating factor) in embryo transfers following devitrification, also known as cryotransfers. It is a simple approach that yields significant results: after thawing, embryos are cultured for two hours in a GM-CSF medium before being transferred to the uterus.
GM-CSF is a natural cytokine produced in the endometrium, particularly in response to ovarian cycle hormones. It plays a key role in embryo implantation, as it enhances communication between the embryo and the uterus, modulates the maternal immune response, and supports early embryo and placental development.
Previous studies had already shown that this medium improved outcomes in patients with recurrent miscarriages. However, until now, its general use in cryotransfers for all types of patients had not been evaluated.

The use of GM-CSF increased the probability of biochemical pregnancy (positive pregnancy test) by 47% and was associated with a significantly higher clinical pregnancy rate (confirmed by ultrasound). Moreover, it halved the miscarriage rate, even in patients with a history of previous failures. These benefits were consistent regardless of the patient’s age or reproductive history.
“This study suggests that the GM-CSF medium is not only useful for patients with implantation failures or recurrent miscarriages, as previously thought, but may benefit any patient undergoing a cryotransfer,” explains Dr Llanos Medrano. In this regard, she states, “Thanks to these results, we have updated the protocol at IVF-Life Alicante and now recommend the use of this medium in all embryo transfer treatments following thawing.”