A Clinical Analysis of Frozen/thawed Embryo Transfer in Spontaneous Cycles

【Objective】To analyze the impact of a number of factors on the pregnancy rate of frozen/thawed embryo transfer in spontaneous cycles【.Methods】A database was analyzed retrospectively concerning frozen/thawed embryo transfer in spontaneous cycles from January 2003 to January 2004 that covered 268 cycles in 233 patients.The factors investigated were maternal age, endometrial thickness, echogenic pattern, hormone levels of luteinizinghormone (LH) surge day, the number of embryos transferred and pregnancy rate per embryo transfer【.Results】Thepregnancies were occurred in 58 cycles of all 268 natural cycles, the pregnancy rate per embryo transfer was21.6%. The mean age of the patients with pregnancy were statistically significant younger than that of the patientswithout pregnancy (30.8±3.0 years vs 31.9±4.0 years, P=0.035). The endometrial thickness on the day of LH surgeat the age of less than 35 years was significant thicker than that at the age of more than 35 years (10.2±1.8 mm vs9.3±2.0 mm, P=0.007). The pregnancy rates were 13.3%, 18.2%, and 23.8% in the cycle of transferred 1, 2, and 3embryos, respectively. However, there was no significant difference in these three groups. There was no significantdifference of endometrial thickness and echogenic pattern, between the pregnancy and the non-pregnancy group.【Conclusion】Our study suggests that the age of female partners can significantly affect the pregnancy rate of frozen/thawed embryo transfer in spontaneous cycles. The pregnancy rate was not influenced by the number of embryos transferred per cycle, endometrial thickness nor echogenic pattern.