Gene expression profile in the endometrium on the day of oocyte retrieval after ovarian stimulation with low-dose hCG in the follicular phase.

The past decade has seen growing interest in ovarian stimulation protocols with GnRH antagonists in an effort to reduce the incidence of potential complications, such as cyst formation and ovarian hyperstimulation syndrome, and thus improve the clinical experience for patients. Current assisted reproductive technique programmes also increasingly utilize milder protocols for ovarian stimulation. In a recently published randomized controlled trial, we showed that low-dose hCG can be utilized clinically to replace recombinant FSH (rFSH) during the late follicular phase in a GnRH antagonist protocol. This regimen leads to a significant reduction in rFSH consumption, while the ICSI outcome, in terms of oocyte yield and ongoing pregnancy rate, remains comparable with the control regimen of rFSH plus a GnRH antagonist. In the present study, the influence of the administration of low-dose hCG on the endometrium was assessed. A comparison was made between two protocols for ovarian stimulation with GnRH antagonists, namely the classical protocol with rFSH and the protocol with low-dose hCG in the late follicular phase. We analysed the morphological pattern and gene expression profile of human endometrium on the day of oocyte retrieval. No morphological differences were observed and only a minimal set of 65 differentially expressed probe sets between the treatment groups were identified, enabling a similar efficacy to support implantation.