Embryo associated immunosuppressor factor(s) secreted by preembryo and serum estradiol levels are predictive of pregnancy outcome: effect of gonadotropin releasing hormone agonist (GnRHa) treatment of patients undergoing in vitro fertilization and embryo transfer (IVF-ET).

The aim of the present study was to determine whether (i) the secretion of embryo associated immunosuppressor factor (EASF) by preimplantation embryo and serum estradiol (E2) play a cooperative role in pregnancy outcome and (ii) whether this association was affected by gonadotropin releasing hormone agonist (GnRHa) pretreatment of IVF-patients for ovarian stimulation. EASF activity was measured using concanavalin A-induced lymphocyte proliferation assay in 251 IVF-culture media obtained from 59 patients undergoing IVF-ET. EASF activity in embryo growth media, cycle day 3 serum E2 level and peak E2 levels were correlated with pregnancy outcome. Results indicate that in GnRHa non-treated patients (i) the immunosuppressive activity of embryo growth media significantly (p less than 0.05) differed between the patients with varying concentration of day 3 serum E2, (ii) the presence of immunosuppressive activity in the embryo growth media was associated with success of pregnancy in patients with day 3 serum E2 level of 21-40 pg/ml (p less than 0.005) and in patients with peak E2 level in serum of less than = 1500 pg/ml (p less than 0.05). No association in immunosuppressive activity, serum E2 level and successful pregnancy was seen in GnRHa treated patients. This preliminary study suggests that the concentration of serum hormones and factors that are altered due to GnRHa pretreatment of IVF-patients may affect the cooperative role played by EASF, E2 and other factors in the success of pregnancy.