A prospective randomized study of the optimum timing of human chorionic gonadotropin administration after pituitary desensitization in in vitro fertilization

Abstract

Objective: To determine if there is an optimum time for the administration of human chorionic gonadotropin (hCG) after pituitary desensitization with gonadotropin-releasing hormone agonists (GnRH-a) has been achieved before ovarian stimulation for in vitro fertilization (IVF).

Design: Prospective randomized study.

Patients: Two hundred forty-seven patients undergoing an IVF treatment cycle who were randomly divided into three groups.

Interventions: All patients were administered subcutaneously buserelin acetate 500 micrograms/d from day 1 of the menstrual cycle. After pituitary desensitization had been achieved at least 14 days later, ovarian stimulation with human menopausal gonadotropin was commenced. Ovarian stimulation, cycle monitoring, oocyte recovery, and IVF and embryo transfer (ET) techniques were identical in all three groups. Patients in group 1 (n = 79) had hCG administered when the mean diameter of the largest follicle had reached 18 mm, at least two other follicles were greater than 14 mm, and serum estradiol (E2) levels were consistent with the number of follicles observed on ultrasound. Patients in groups 2 (n = 84) and 3 (n = 84) had hCG administered 1 day and 2 days, respectively, after the above criteria had been reached.

Results: The mean day of hCG administration (P less than 0.01), maximum serum E2 concentration (P = 0.06), number of days of serum E2 rise (P = 0.03), and mean diameter of the largest follicle (P less than 0.0001) were significantly different. There were, however, no significant differences in the mean number of preovulatory and medium size follicles, number of oocytes recovered or embryos transferred. There were also no significant differences in the oocyte recovery, fertilization and cleavage rates, in the number of embryos frozen, or in the pregnancy rates per initiated cycle and per ET.

Conclusions: There is no significant advantage in the precise timing of hCG administration after pituitary desensitization with GnRH-a.