Comparison Of Pregnancy Outcome Safety Between Cleavage Stage Embryo Transfer And Blastocyst Transfer

After the first test-tube baby born in England in1978, the ART represented byin vitro fertilization and embryo transfer (IVF-ET) has been developing more than30years. Most IVF clinics transfer the cleavage stage embryos in their IVF orintracytoplasmic sperm injection (ICSI) practices. Due to the low implantation rateof cleavage stage embryos, many clinics transfer2~3cleavage stage embryos toinsurance clinical pregnancy rate, and this results in high multiple pregnancy rate. Inrecent years, the blastocyst formation rate and the quality of blastocyst have beenimproved greatly for using of sequential medium. Blastocyst culture lets thecleavage stage embryos has been further screened, and greatly improved theimplantation rate. Nowadays, many IVF clinics transfer blastocyst stage embryos toreduce multiple pregnancy rate, especially apply elective single blastocyst transfer(eSBT) for patients meet certain conditions. The sequential culture of blastocyst iswidely accepted, though it gives different culture conditions in different embryonicdevelopment periods, but it’s still has a big difference from physiologicalenvironment in the fallopian tubes and uterus for embryos, the embryos may haveepigenetic marks for being affected by the culture medium when extend the period ofin vitro cultivation (blastocyst culture). Therefore, whether it would increase the risk of adverse pregnancy outcome when culturing the cleavage stage embryos to theblastocyst stage? With more and more blastocyst stage embryo transfer application,we need to evaluate the safety of pregnancy outcome after embryo transfer indifferent development stages, and providing guidance for clinical practices.ObjectiveThis study compared the embryo implantation rate, clinical pregnancy rate,multiple pregnancy rate, high order multiple pregnancy rate, monozygotic twins rate,reduction ratio, miscarriage rate, ectopic pregnancy rate, premature birth rate,postterm delivery rate, live births rate, cesarean section rate, male/female birth ratio,the perinatal mortality, incidence of birth defects, the incidence of low birth weightinfant and macrosomia between cleavage stage embryo transfer and blastocysttransfer. To evaluate the safety of pregnancy outcome after embryo transfer indifferent development stage, providing guidance for clinical practice.Material and MethodsThis study retrospectively analyzed the clinical data of5688cycles of in vitrofertilization-embryo transfer(IVF-ET) or intracytoplasmic sperm injection(ICSI) inthe Reproductive Medicine Center of the First Affiliated Hospital of ZhengzhouUniversity from April2011to March2013. It included5184cycles of cleavage stageembryo transfer (group D3, including fresh cycles and freeze-thaw cycles) and504cycles of blastocyst transfer (group D5, including fresh cycles and freeze-thawcycles). The two group were then divided into:2784fresh cycles of cleavage stageembryo transfer (group D3A),2400freeze-thaw cycles of cleavage stage embryotransfer(group D3B),356fresh cycles of blastocyst transfer (group D5A),148freeze-thaw cycles of blastocyst transfer(group D5B). Outcomes were compared,such as the clinical pregnancy rate, embryo implantation rate, multiple pregnancy rate,monozygotic twins rate, reduction ratio, miscarriage rate, ectopic pregnancy rate,premature birth rate, postterm delivery rate, live births rate, cesarean section rate, male/female birth ratio, perinatal mortality, incidence of birth defects, incidence oflow birth weight infant and macrosomia between cleavage stage embryo transfer andblastocyst transfer.Results1.The clinical pregnancy rate, multiple pregnancy rate, premature birth rate, livebirth rate, cesarean section rate and the incidence of low birth weight infant of groupD3is higher than group D5(52.10%vs43.45%,32.88%vs10.50%,16.67%vs6.29%,42.61%vs34.52%,84.77%vs78.29%,19.50%vs8.11%, P<0.05). Theembryo implantation rate of group D3is lower than group D5(31.00%vs38.89%,P<0.05). The male/female birth ratio of group D5is higher than group D3(1.20vs1.09), but there is no significant difference(P>0.05). There is no significantdifference in other outcome parameters between group D3and group D5(P>0.05).2.The clinical pregnancy rate, multiple pregnancy rate, premature birth rate, livebirth rate, cesarean section rate, the perinatal mortality and the incidence of low birthweight infant of group D3A is higher than group D5A(59.81%vs46.35%,38.32%vs2.53%,17.00%vs4.55%,50.07%vs37.08%,83.79%vs75.00%,1.43%vs0,21.50%vs5.19%, P<0.05). The embryo implantation rate and monozygotic twinsrate of group D3A is lower than group D5A(39.25%vs44.39%,0.60%vs2.42%,P<0.05). The male/female birth ratio of group D5A is higher than group D3A(1.21vs1.08), but there is no significant difference(P>0.05). There is no significantdifference in other outcome parameters between group D3A and groupD5A(P>0.05).3.The ectopic rate and embryo implantation rate of group D3B is lower thangroup D5B(0.87%vs5.56%,22.54%vs29.55%, P<0.05). The male/female birthratio of group D5B is higher than group D3B (1.17vs1.10), but there is nosignificant difference(P>0.05).There is no significant difference in other outcomeparameters between group D3B and group D5B(P>0.05). ConclusionsBlastocyst stage embryo transfer is an effective measure to reduce multiplepregnancy rate, premature birth rate and incidence of low birth weight. It does notincrease the risk of birth defects, but may reduce the clinical pregnancy rate and livebirth rate, increase the incidence of monozygotic twins, male/female sex ratio ofbirth and other risks. Choice of selecting cleavage stage embryo transfer orblastocyst stage embryo transfer should be carefully made in IVF/ICSI clinicalpractices.