Estradiol Supplementation Therapy during Controlled Ovarian Hyperstimulation in Patients of IVF-ET with Thin Endometrium

It is known that adequate endometrial thickness is an important prognostic factor for implantation in natural cycles, in assisted conception cycles employing ovulation induction and ovum recipient cycles using hormone replacement therapy. Recently the thickness of the endometrium has been highly correlated with histological maturation, and in patients with thin endometrium increased dosage and duration of estradiol supplementation has led to increased endometrial maturation thus stressing the importance of endometrial thickness. In this study, the results of estradiol supplementation in patients with abnormally thin endometrium who are undergoing IVF-ET was observed and to evaluate the endometrial response and to compare the pregnancy outcome. From November 1st, 1994 to August 31st, 1997, 491 IVF-ET cycles were studied, which were divided into several groups. The first group was 451 cycles where the endometrial thickness was more than 7mm at the time of hCG injection, the second group was 15 cycles where the endometrial thickness was less than 7mm at the time of hCG injection, the third and fourth group was where the endometrial thickness was less than 7mm from the previous cycle to the time of hCG injection, in which the third group was 12 cycles where embryo transfer was not completed immediately but later after freezing, and in which the fourth group was 13 cycles which received estradiol supplementation during ovulation induction. The endometrial thickness averaged 10.0±0.1 mm in Group 1 and only 5.8±0.1mm in Group 2, but after estradiol supplementation which resulted in longer endometrial exposure to estrogen, 7.9±0.5 days in Group 2, 19.8±0.7 days in Group 3, 16.7±0.9 days in Group 4, showing significant increase[p＜0.05]. In Group 3, 11 of 12 cases, and 10 of 13 cases in Group 4 the endometrial thickness improved to more than 7mm, along with the average thickness which increased to 7.1± 0.5 mm and 8.3±0.5 mm, respectively. There was no significant difference with regard to number of embryos transferred, cumulative embryo score, number of embryos of more than Grade II-1 between the groups. The clinical pregnancy rate and ongoing pregnancy 27.7% and 22.3% respectively, but in Group 2 the clinical pregnancy rate was only 6.6%. However, in Group 3 and Group 4 where estradiol supplementation was administered, the clinical pregnancy rates were 25.0% and 38.5% respectively, and the pregancy rates beyond 12 weeks of gestation reached 25.0% and 30.8% respectively. In conclusion, in cases where thin endometrium is observed at the time of hCG injection during IVF-ET it is recommended to freeze the embryo and then conduct the transfer after prolonging the length of estradiol administration, but in cases where the the endometrium is not adequate in the previous cycle or during basic infertility work-up, it is suggested that estradiol supplementation to long protocol GnRHa is effective.restrictio