Effect Of Human Chorionic Gonadotropin On Pregnancy Outcome In Natural-cycle Frozen Thawed Blastocyst Transplantation

Background:With the improvement of embryo freezingand the development of blastocyst culture,blastocyst frozen is gradually becoming a conventional technique in assist reproductive medicine.The synchronism of endometrial maturity and embryonic development is the prerequisite for embryo implantation.At present,the commonly used methods for endometrial preparation include natural-cycle,estrogen replacement cycle,and superovulation cycle,etc.The natural-cycle program simulates the natural pregnancy process.It is the preferred endometrial preparation program for patients with regular menstrual cycle.It can determine the ovulation time according to the occurrence of endogenous LH peak and B-mode ultrasound monitoring,or the ovulation can be induced by human chorionic gonadotropin(HCG).Embryo implantation is a physiological process regulated by many factors,and HCG is one of the most closely related molecular signals.So far,most studies have suggested that the use of HCG induced ovulation has no significant effect on the outcome of frozen embryo transplantation.However,it is reported that the use of HCG to induce ovulation reduces the clinical pregnancy rate in the natural-cycle frozen embryo transplantation,which is considered to be possibly related to the mechanism of HCGonendometrialreceptive.Prior studies have paid much attention to the effect of HCG on frozenthawed embryo transplantation during cleavage stage.In this paper,the effect of HCG induced ovulation on pregnancy outcome was investigated in natural-cycle frozenthawed embryo transplantation.Objective:In this study,a prospective randomized controlled trial was conducted to explore whether the use of HCG induced ovulation affected the outcome of pregnancy in natural-cycle frozenthawed blastocyst embryo transplantation.Methods:A total of 205 cases of patients were included into this study in the Reproductive Hospital Affiliated to Shandong University from May 2014 to February 2015.Eventually,192 cases were included following the exclusion of 13 patients,including 8 cases without ovulation or the endometrial thickness<8mm at the day of ovulation,2 cases of refusal to participate,and 3 cases abandoning transplantation for other factors.The recruitment criteria were strictly controlled.Patients were randomly divided into the HCG group(98 cases)and non HCG group(94 cases).According to the history of pregnancy,enrolled patients were divided into the primary infertility group(n = 126;HCG group,n = 67,control group,n = 59),and the secondary infertility group(n = 66;HCG group,n = 31,non-HCG group,n = 35).Furthermore,the clinical pregnancy rate,the survival rate and the abortion rate were statistically analyzed.Results:1、Clinical features and pregnancy outcome of included patients:There was no significant difference in age,endometrial thickness at the day of ovulation,number of transplanted embryos and causes of infertility in the HCG group and the control group(P>0.05).Compared with the control group,the clinical pregnancy rate,the survival rate,and the abortion rate were increased in patients of the HCG group,but the difference was not statistically significant(P>0.05).2、Comparison of clinical characteristics and pregnancy outcome in patients with primary and secondary infertility:The age of the group with secondary infertility was higher than that of the primary infertility group,but without statistical difference.In patients with secondary infertility,the clinical pregnancy rate of the HCG group was lower than that of the control group(51.6%vs 82.9%),indicating statistical difference(P<0.001).Meanwhile,the survival rate was significantly decreased than that of the control group(41.9%vs 77.1%),and the difference was statistically significant(P<0.001).Conclusions:In the process of natural-cycle freezethawedblastocyst transplantation,the use of HCG induced ovulation has no significant effect on the clinical pregnancy rate and the survival rate of patients.For patients with secondary infertility,the use of HCG to induce ovulation may have adverse effect on the clinical pregnancy rate and the survival rate.