Ratio of oestradiol concentration on the day of human chorionic gonadotrophin administration to mid-luteal oestradiol concentration is predictive of in-vitro fertilization outcome.

The role of luteal oestradiol for successful implantation in humans seems to be permissive rather than obligatory. Few studies have attempted to clarify the role of early luteal oestradiol in in-vitro fertilization (IVF) outcome, whether peri-implantation oestradiol is predictive of successful IVF outcome. We retrospectively analysed 106 women undergoing 106 IVF/embryo transfer cycles. Only the first treatment cycle per patient was analysed. Peak oestradiol denoted the concentration on the day of human chorionic gonadotrophin (HCG) administration. Mid-luteal oestradiol was obtained 3 days after embryo transfer (8 days after HCG administration). A total of 44 pregnancies were noted (41.51%). There were no differences in age, cycle day 3 follicle stimulating hormone (FSH), peak oestradiol, number of retrieved oocytes, number of embryo transfers, and mid-luteal oestradiol between pregnant and non-pregnant women. However, the ratio of day of HCG oestradiol to mid-luteal oestradiol was highly predictive of successful outcome: the ongoing pregnancy rate and implantation rate (sacs with fetal heart beat/embryo transfer) were 15.8 and 5.7% respectively if the above ratio exceeded 5.0 (n = 19), compared to 42.1 and 16.3%, and 53.3 and 26. 5% if the ratio was between 0.4 and 2.5 (n = 57), and between 2.5 and 5.0 (n = 30) respectively. Our study suggests that the magnitude of decline in oestradiol concentrations after oocyte retrieval may be important in predicting IVF success. We postulate that endometrial integrity may become compromised when a dramatic drop in oestradiol occurs by the mid-luteal period. Whether these women benefit from oestradiol supplementation after oocyte retrieval remains to be investigated.