# The Role of Granulocyte Colony-Stimulating Factor in Endometrial Preparation for Embryo Implantation in In Vitro Fertilization

## TL;DR

This review explores how G-CSF can help prepare the endometrium for embryo implantation in IVF, showing it works best for specific patient groups.

## Contribution

The paper identifies G-CSF as a phenotype-specific endometrial conditioning strategy rather than a general IVF supplement.

## Key findings

- G-CSF reliably increases endometrial thickness in patients with thin endometrium.
- It improves implantation outcomes in patients with recurrent implantation failure through immune-stromal mechanisms.
- No benefit is observed in unselected IVF populations, highlighting the importance of patient selection.

## Abstract

Granulocyte colony-stimulating factor (G-CSF) has been suggested as a supplementary approach for endometrial preparation in IVF. Clinical results continue to be inconsistent. This narrative review synthesises molecular and clinical information to elucidate the function of G-CSF in modifying endometrial receptivity and to identify patient categories most likely to benefit. A thorough assessment was conducted on published research on G-CSF administration in women with treatment-resistant thin endometrium, recurrent implantation failure, and unselected IVF populations. The research demonstrates that G-CSF has phenotype-dependent effects. Improvements in pregnancy and live birth rates are inconsistent and seem dependent on the reversibility of underlying tissue disease; nevertheless, G-CSF reliably increases endometrial thickness in instances of thin endometrium and may restore eligibility for transfer. G-CSF improves implantation and early pregnancy outcomes in repeated implantation failure patients without modifying endometrial morphology, indicating a functional mechanism linked to immune-stromal synchronisation rather than structural expansion. In contrast, randomised controlled studies show no therapeutic benefit in unselected IVF groups. Discrepancies in research outcomes may mostly be attributed to variations in patient phenotype, initial endometrial function, and the therapy setting. Thus, G-CSF should be considered a specific approach for endometrial conditioning rather than just a supplementary component of IVF.