Background: Elevated serum progesterone levels at the end of the follicular phase in controlled ovarian stimulation (COS) leads to a poorer ongoing pregnancy rate in IVF cycles due to reduced endometrial receptivity. The objective of this study was to use microarray technology to compare endometrial gene expression profiles at the window of implantation according to the levels of circulating progesterone.
Methods: For this prospective cohort study, microarray data were obtained from endometrial biopsies from 12 young healthy oocyte donors undergoing COS with pituitary suppression by either gonadotrophin-releasing hormone (GnRH) agonists or antagonists, and recombinant FSH. On the day of recombinant chorionic gonadotrophin (rCG) administration, six women had serum progesterone levels (P) >1.5 ng/ml (study group) and six had serum P levels <1.5 ng/ml (control group). Endometrial samples were collected using a Pipelle catheter 7 days after the rCG injection.
Results: Using the parametric test, we identified 140 genes significantly dysregulated (64 up- and 76 down-regulated) in the study group endometria compared with the control endometria, regardless of the GnRH analogue employed. These genes are related to cell adhesion, developmental processes, the immune system and others, which are all required for normal endometrial function development. Of the 25 gene targets previously proposed as markers for endometrial receptivity, 13 appeared over-regulated in the study group.
Conclusions: Our results reveal that elevated progesterone levels on the day of rCG administration can induce significant alterations in the gene expression profile of the endometrium.