Abstract:

Objective To analyse the effects of serum estradiol levels during controlled ovarian hyperstimulation (COH) on the outcomes of in vitro fertilization and embryo transfer (IVF-ET). Methods The clinical data of 472 patients undergoing IVF-ET with GnRH analogues recombinant FSH long protocol were retrospectively analysed. The area under the curve (AUC) of estradiol (E₂) level was calculated during COH, and patients were categorized into groups according to the percentile of AUC of E₂ (AUC_E2) during COH. The general characteristics and parameters related to the outcomes of IVF-ET were compared among groups. Results The 10th percentile and 90th percentile of AUC_E2 were 3 347.0 pmol/L and 14 414.3 pmol/L, respectively. Four hundred and seventytwo patients were divided into lower reaction group (AUC _E2≤3 347.0 pmol/L, n=48), normal reaction group (14 414.3 pmol/L>AUC_E2>3 347.0 pmol/L, n=376) and higher reaction group (AUCE2≥14 413.3 pmol/L, n=48). There was no significant difference in age, body mass index, baseline follicle stimulating hormone level, time of treatment with gonadotropin, endometrium thickness on day of transfer and embryos transferred（P>0.05）. Compared with lower reaction group and normal reaction group, the number of oocytes per retrieval and number of embryos frozen were significantly larger（P<0.01）and the mild/severe ovarian hyperstimulation syndrome rate was significantly higher in higher reaction group（P<0.05）. There was no significant difference in fertilization rate, cumulative embryo score, high-grade embryo rate, clinical pregnancy rate and implantation rate among groups (P>0.05). Conclusion Sustained supraphysiological serum E₂ levels during the COH process do not adversely affect the quality of oocytes and embryos, clinical pregnancy rate and implantation rate to some extent in IVF-ET.

Key words: controlled ovarian hyperstimulation, estradiol, pregnancy rate, implantation rate