Ovarian stimulation for in vitro fertilization alters the intrauterine cytokine, chemokine, and growth factor milieu encountered by the embryo.

Objective: To elucidate the impact of ovarian stimulation on the intrauterine milieu represented by the cytokine, chemokine, and growth factor profile in endometrial secretions aspirated before embryo transfer.

Design: Prospective cohort study.

Setting: Fertility center in tertiary referral university hospital.

Patient(s): Forty-two patients undergoing ovarian stimulation with GnRH analogues were recruited. They participated in both a natural and an ovarian-stimulated cycle for within patient comparisons.

Intervention(s): Endometrial secretion aspiration was performed immediately before embryo transfer.

Main Outcome Measure(s): The concentrations of 17 mediators known to be involved in human embryo implantation were assessed by multiplex immunoassay.

Result(s): After correction for multiple testing, significantly higher concentrations of interleukin (IL)-1β, IL-5, IL-10, IL-12, IL-17, tumor necrosis factor (TNF)-α, heparin-binding epidermal growth factor (HbEGF), eotaxin, and dickkopf homologue-1 were present in endometrial secretions obtained in stimulated compared with natural cycles.

Conclusion(s): Endometrial secretion analysis provides a novel means of investigating the effect of ovarian stimulation on the intrauterine milieu. The in vivo milieu encountered by the embryo after transfer is significantly altered by ovarian stimulation.