Descriptive Analysis of Serum Immunological Markers During an Euploid Frozen Embryo Transfer in a Natural Cycle.

To describe the peripheral serum levels of the anti-inflammatory cytokines IL-4 (Interleukin-4), IL-10 (Interleukin-10), TGF-ß1 (Transforming Growth Factor beta1), the pro-inflammatory cytokines IL-17 (Interleukin-17), IFγ (Interferon Gamma) and the immune mediator PIBF (Progesterone-Induced Blocking Factor) along a single frozen euploid blastocyst transfer in a natural cycle (NC) or Hormone Replacement Therapy (HRT).

This a prospective, observational study including 40 infertile patients undergoing a "single embryo transfer" (SET). Blood samples will be drawn for Progesterone-Induced Blocking Factor (PIBF), interleukin 17 (IL-17), Interferon Gamma (IFγ), Interleukin 10 (IL-10), Interleukin 4 (IL-4) and Transforming Growth Factor beta 1 (TGF-ß1) measurement on the day of ovulation in the natural cycle (NC) or first day of progesterone in the Hormone Replacement Therapy (HRT) protocol, on the day of embryo transfer (ET) and 3 and 10 days later, coinciding with the early and late embryo invasion stages respectively. In case of pregnancy, an additional blood test for PIBF, IL-17, IFγ, IL-10, IL-4, TGF-ß1 and ßHCG (Beta-Human Chorionic Gonadotropin) will be performed at 5 weeks +/- 3 days. The study will be performed at ART Fertility Clinics and the estimated completion time will be 12 months.