[Impact of controlled ovarian hyperstimulation delayed, which occurs after functionally pituitary downregulation by depot GnRH agonist, on the outcome of in vitro fertilization and embryo transfer].

OBJECTIVE: This study observed the influence on hormone, embryos and clinical outcomes when the starting time of controlled ovarian hyperstimulation (COH) was delayed after applying a half-dose depot gonadotropin-releasing hormone agonist (GnRHa).

METHODS: A total 207 cycles were divided into 3 groups: control group (98 cycles, which performed daily low dose GnRHa during the mid-luteal phase in patients' menstrual cycles and reduced the dosage to a half at the next day 3, and added gonadotropin (Gn), conventional group (63 cycles, in which pituitary desensitization was obtained with a half-dose depot GnRHa in the mid-luteal phase, and then Gn was added at day 3) and delayed group (46 cycles, having the same usage of GnRHa to conventional group, but not adding Gn until day 7).

RESULTS: The cancellation rate of cycle in conventional group was the highest (P < 0.01). At the beginning of COH, serum E2 and LH levels in delayed and control group were significantly higher than those in conventional group (P < 0.01). On the day of HCG given, serum E2 level in control group was the highest (P < 0.05). LH level in delayed and control group was higher than that in conventional group (P < 0.01). Concerning the clinical efficacy and outcome, the numbers of Gn ampoules and periods for stimulation were less in delayed group than in conventional group; the numbers of retrieved and fertilized oocytes, numbers of good quality embryos, clinical pregnancy rate and embryo implantation rate in delayed and control groups were significantly more than those in conventional group (P < 0.01). In ICSI cycles, the numbers of retrieved oocytes and metaphase II oocytes in delayed and control group were more than those in conventional group.

CONCLUSIONS: A half-dose depot GnRHa may produce over suppression to pituitary gland in fertilization in vitro, appropriate delay of COH starting time can decrease ovarian stimulation period and ampoules of Gn, and increase retrieved good quality oocytes, so we could achieve a larger number of good quality embryos with a good chance of implantation.