Factors Of Early Spontaneous Abortion In Frozen-Thawed Enbryo Transfer

OBJECTIVE:To investigate the correlation factors of early spontaneous abortion in frozen-thawed embryo transfer.METHODS:The research was conducted by retrospective analysis of the data between June 2009 and August 2010 from the pregnancy patients who received frozen-thawed embryo transfer in the center for Reproductive Medicine, Provincial Hospital Affiliated to Shangdong University. There were 384 pregnancy patients who accepted IVF/ICSI for gametes transporting barriers and (or) male sterile factors, excluding endometriosis, endometrial polyps, reproductive system malformation, hyperprolactinemia and other diseases affecting pregnancy. Men had normal chromosomes and AZF/CFTR gene in every ICSI cycle. Divide all the 385 cycles into abortion group (56 cases) and non-abortion group (70 cases) according to the pregnancy outcome. Take their age, infertility duration, basic sex hormone, BMI, abortion history, fertilization method, fertilization rate and high-quality embryos rate in stimulated cycle, endometrial preparation method, thickness of endometium on ET day, embryos quality after thawing, number of high-quality embryos transferred and implantation rate into analysis to find the correlation factors of spontaneous abortion in thawing cycles.RESULTS:1. The age of the couples and infertility duration of abortion group were significantly higher than those of non-abortion group(P<0.05), while there was no significant difference in basic sex hormone and BMI(P>0.05).2. Patients who experienced previous abortion had significantly higher early abortion rate than other patients (P<0.05).3. The high-quality embryos rate in stimulated cycle and implantation rate in thawing cycle of abortion group was significantly lower than those of non-abortion group(P<0.05). While there were no significant difference in fertilization method, endometrial preparation method, thickness of endometium on ET day(P>0.05). The early abortion rate of bigeminal or multiple pregnancy was significantly lower than those of the singleton pregnancy(P<0.05).4. Transfer embryos continuing to cleave after thawing resulted lower abortion rate compared with that of transfer embryos with no further cleavage(P<0.05). Blastmeres were damaged in 66 cycles, which were divided into 3 groups:<2/24,≥2/24 and <6/24,≥6/24.The last group resulted in the highest abortion rate compared with the other groups(P<0.05).And transfer of 2 fully intact embryos resulted in the significantly lower abortion rates compared with transfer of 1 or no fully intact embryos (P<0.05).CONCLUSION:1. The age of the couples, infertility duration, abortion history and the number of pregnancy embryo can significantly affect the success of frozen-thawed embryo transfer. And fertilization method, BMI, endometrial preparation method, thickness of endometium on ET day is not related to the abortion of frozen-thawed embryo transfer.2. The high-quality embryos rate in stimulated cycle and embryos quality after thawing is closely related to the early abortion. Transfer embryos continuing to cleave after thawing resulted in the lower abortion rate. The less of blastomere survival and less of fully intact embryos transferred resulted in the higher abortion rate. Our study suggests that the quality of transferred embryos is important factor influencing the early abortion of frozen-thawed embryo.