OBJECTIVETo investigate the value of serum estradiol increment and serum estradiol/follicles on the day of hCG administration in predicting the clinical outcomes of in vitro fertilization-embryo transfer (IVF-ET).

METHODSA retrospective analysis of the IVF-ET data was conducted involving 121 patients who received a long gonadotrophin-releasing hormone agonist (GnRHa) protocol. According to the increment of serum estradiol on the day of hCG administration (relative to the level on the day before hCG administration), the patients were divided into 3 groups (A1, A2 and A3) with a increment ratio below 30%, between 30% and 50%, and over 50%, respectively. In addition, according to the ratio of serum estradiol level on hCG day to mature follicle (diameter ≥ 14 mm) number, these patients were divided into three groups (B1, B2 and B3) with the ratio below 250 pg/ml, between 250 and 350 gp/ml, and over 350 pg/ml, respectively. The hormonal characteristics and clinical outcomes of the IVF-ET cycles were analyzed comparatively.

RESULTSBoth the clinical pregnancy rate (71.05%) and embryo implantation rate (52.63%) were significantly higher in group A3 than in groups A1 and A2 (P<0.05). The best clinical pregnancy rate (67.86%) and embryo implantation rate (49.14%) were significantly higher in group B2 than in groups B1 and B3 (P<0.05).

CONCLUSIONThe variation of serum estradiol shows an important impact on the clinical outcomes of IVF-ET in patients receiving long GnRH-a protocol. Favorable outcomes can be expected with a hCG day serum estradiol increment ratio above 50% and E(2)/follicle ratio between 250 and 350 pg/ml.