High serum oestradiol concentrations in fresh IVF cycles do not impair implantation and pregnancy rates in subsequent frozen-thawed embryo transfer cycles

High oestradiol concentrations may be detrimental to the success of in-vitr o fertilization (IVF) treatment. A total of 1122 women aged <40 years who w ere undergoing their first IVF circle mere evaluated retrospectively. Serum oestradiol concentrations on the day of human chorionic gonadotrophin (HCG ) administration mere categorized into three groups: group A <10 000 pmol/l ; group B 10 000-20 000 pmol/l and group C >20 000 pmol/l, In fresh cycles, group A had significantly lower pregnancy rates per transfer (16.2 versus 23.7% respectively, P = 0.005, chi(2)) and implantation rates (8.7 versus 1 1.7% respectively, P 0.037, chi(2)), when compared with group B. The pregna ncy rate per transfer in group C was significantly lower than that in group B (12.1 versus 23.7%, P = 0.049, chi(2)) and group C had the lowest implan tation rate (6.4%). In frozen-thawed embryo transfer cycles, implantation r ates in groups A, B and C mere similar (7.5, 8.1 and 9.6% respectively) and the pregnancy rates mere also comparable in all groups. In conclusion, hig h serum oestradiol concentrations in fresh IVF cycles may adversely affect implantation and pregnancy rates, Embryo quality seemed unaffected as exces s embryos from different groups had similar implantation and pregnancy rate s in frozen-thawed embryo transfer cycles. The reduced implantation was pro bably due to an adverse endometrial environment resulting from high serum o estradiol concentrations.