LOWER IMPLANTATION RATES IN HIGH RESPONDERS - EVIDENCE FOR AN ALTEREDENDOCRINE MILIEU DURING THE PREIMPLANTATION PERIOD

Objective: To determine serum E(2) and P levels around the time of imp lantation in normal and high IVF responders. Setting: In Vitro Fertili zation program at the Institute Valenciano de Infertilidad. Patients: Twenty-nine women undergoing IVF, who accepted to be studied daily, we re classified according to the number of oocytes retrieved in normal ( n = 16) and high responders (n = 13). Design: Prospective study in whi ch blood was drawn daily from the day of hCG administration (day 0) up to 7 days later (day 6). Main Outcome Measurements: In vitro fertiliz ation parameters (number of ampules, FSH-hMG, number of oocytes, ferti lization rates, number of transferred embryos, implantation rates, and pregnancy rates); serum E(2) and P levels during the 7 days of the st udy. Results: Implantation rate was significantly higher in normal (18 .5%) as compared with high (0%) responders. Estradiol and P levels wer e elevated significantly in high responders. The E(2):P ratio was sign ificantly different between normal and high responders during the prei mplantation period. Pregnancy and implantation rates decreased as seru m E(2) levels increased on days 4 to 6 of the study. Conclusions: A di fferent endocrine milieu between normal and high responders is detecte d by daily steroid measurements up to the preimplantation period, sugg esting that this difference could be responsible for an impaired impla ntation in high responder patients undergoing IVF. An increase in seru m E(2) levels seems to be the cause of this difference.