Objective To study the effect of desogestrel and ethinyl estradiol(DEE)pre-treatment combined with gonadotropin releasing hormone agonist(GnRH-a)stimulation in in vitro fertilization-embryo transplantation(IVF-ET).MethodsA retrospective analysis was performed in 101 infertile women who received a short protocol of GnRH-a for IVF-ET treatment from June 2004 to June 2007 in the Reproductive Medicine Center of First Affiliated Hospital of Wenzhou Medical College.Patients had been pre-treated with oral contraceptive pill(OCP)for two months before GnRH-a combined with recombinant follicle stimulation hormone(r-FSH)treatment(study group,n=42)or had not been pretreated with OCP(control group,n=59).A statistical analysis of two groups was carried out for the assessment of ovulation stimulating effect of OCP and its influence on the IVF.Results Serum FSH was significantly decreased after OCP in the study group.Twelve pregnancies were obtained including 1 case of spontaneous abortion at 7 weeks in the study group,and 11 pregnancies were obtained including 2 cases of spontaneous abortion during 7-9 weeks in control group.The clinical pregnancy rates in the study group(23％,12/53)was higher than that in the control group(17％,11/63),but the differences were not significant(P＞0.05).The miscarriage rate in the study group(8％,1/12)was lower than that in the control group(18％,2/11),however no significant differences were found between them(P＞0.05).The cycle cancellation rate in patients of the study group(5％,3/56)was significantly lower than that in patients of the control group(17％,13/76,P＜0.05).The differences between patients of the two groups with respect to age,basal level of FSH and luteinizing hormone (LH),antral follicle counts,the mean number of oocyte retrieval,the days of stimulation,total dose of rFSH used,fertilization rate and embryo cleavage rate,however were insignificant.ConclusionOCP pretreatment combined with short protocol of GnRH-a stimulation in IVF could significantly decrease the cycle cancellation rate,with a declining miscarriage rate and increasing pregnancy rate.