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

ObjectiveTo 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.DesignProspective cohort study.SettingFertility 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.