Can serum oestradiol be a predictor of quality of oocytes and embryos, maturation of oocytes and pregnancy rate in ICSI cycles?

Our aim was to assess the influence of ratios of oestradiol (E2) to either number of follicles ≥ 14 mm on the day of human chorionic gonadotropin administration (E2/fol) or the number of oocytes retrieved (E2/o) during oocyte pick up and total serum E2 levels on the day of embryo transfer (ETE2) on the outcome of ICSI cycles. The assessed outcomes were number of oocytes retrieved (NRO), number of mature oocytes (NMO), number of fertilised oocytes (NFO), number of transferred embryos (NTE), qualities of oocytes (OQS), qualities of embryos (EQS) and pregnancy rates (PR). Two hundred and twenty-seven ICSI-ET cycles admitted to our IVF clinic during a 2-year period with normal ovarian reserve receiving long luteal GnRH agonist protocol were included. The E2/fol levels correlated positively with NRO (r = 0.202, p = 0.002), NMO (r = 0.199, p = 0.003) and NFO (r = 0.159, p = 0.018). However, we observed negative correlations between E2/o and NMO (r = -0.329, p <0.001), NFO (r = -0.219, p = 0.001), EQ5 (r = -0.203, p = 0.040). Oocyte quality scores were not affected from either E2/fol or E2/o levels. Implantation, clinical and ongoing PRs were comparable between groups categorised due to E2/fol, E2/o and ETE2. It seems that high E2/fol ratio may have beneficial effects on NRO, NMO and NFO while E2/o may adversely affect these parameters. Neither of the E2 levels is associated with pregnancy rates in women with normal ovarian reserve.