Objective   To evaluate the value of pituitary down-regulation induced by gonadotrophin releasing hormone agonist (GnRH-a) in the outcome of in vitro fertilization-embryo transfer (IVF-ET).   Methods   Totally 185 cases

which involved 187 cycles undergoing IVF/intracytoplasmic sperm injection (ICSI) treatment

admitted in our reproductive medicine center from Jan. to Dec.  2008 were retrospectively analyzed. All patients got triptorelin 0.05 mg per day from mid-luteal phase of the prior menstrual cycle (day18 to 21). According to the level of pituitary down-regulation before controlling ovarian hyperstimulation (COH)

patients were divided into 2 groups: full-down-regulation group (group A

95 cycles) and not full-down-regulation group (group B

92 cycles). Their age

doses of GnRH-a and gonadotropine (Gn)

number of retrieved oocytes and metaphase Ⅱ oocytes

fertilization rate

high quality embryos and clinic pregnancy rate were compared.   Results   The rate of clinic pregnancy in the group A was obviously higher than that in group B (48.94% vs 32.61%

P0.05). No difference was observed in the abortion rate. Although no difference observed among the doses of GnRH-a and Gn

number of retrieved oocytes and metaphase Ⅱ oocytes and fertilization rate in 2 groups

the high quality embryos in group A was significantly higher than group B (43.70% vs 31.80%

P0.05).   Conclusion   Complete and proper pituitary down-regulation induced by GnRH-a in long protocol exerts great influence on the outcome of IVF treatment. The standard used in our reproductive center could be a good choice during the pituitary down-regulation.