Abstract: Objective：To investigate the outcome of reducing the dose of gonadotropin releasing hormone agonist (GnRHa) and controlling the dose of gonadotropins (Gn) starting in the long-down-regulation protocol for those poor ovarian response (POR) patients. Methods: The POR patients undergoing the long-down-regulation protocol with 1.0 mg GnRHa in our center from December 2015 to July 2017 were randomly divided into the group A and B. The Gn starting dose of the group A was 150-225 IU, and the Gn starting dose of the group B was 300-450 IU. Total dose of Gn, the days of Gn using, the estradiol (E2) level on the day of hCG injection, the number of retrieved oocytes, the fertilization rate, the number of excellent embryos, the number of transplantable embryos, and the clinical pregnancy rate were compared between the two groups. Results: There were 285 cycles of obtained-oocytes in the group A, while 292 cycles in the group B. The total dose of Gn and the E2 level on the day of hCG injection in the group A were significantly lower than those in the group B (P＜0.05), the total days of Gn using was significantly more than the group B (P＜0.05). There were no statistical differences in the number of obtained oocytes, the fertilization rate, the number of transplantable embryos and the number of excellent embryos between the two groups (all P＞0.05). Interestingly, the clinical pregnancy rate in the group A was statistically higher than that in the group B (P＜0.05). Conclusions: For those POR patients undergoing IVF-ET, reducing the dose of GnRHa and controlling the dose of gonadotropins startings in the long-down-regulation protocol can improve the IVF outcome and reduce their cost of ovulation drug treatment.

Key words: Fertilization in vitro, Embryo transfer, Gonadotropin-releasing hormone, Poor ovarian response, Gonadotropins