Single blastocyst transfer minimizes multiple pregnancy rate without hindering pregnancy rate compared to double blastocysts transfer in certain age group

Abstract

OBJECTIVE: Although ART has been used widely, lately multiple pregnancy is a serious issue. Multiple embryos are transferred to maintain high pregnancy rate and it causes high incidence of multiple pregnancy. Single cleaved stage embryo transfer has been attempted to minimize multiple pregnancy rate, but it decreased pregnancy rate. Recently, blastocyst transfer is performed, and high pregnancy and implantation rates are reported. Therefore, the present study was conducted to determine whether single blastocyst transfer could prevent multiple pregnancy without hindering pregnancy rate compared to double blastocysts transfer. DESIGN: Retrospective clinical study at private clinic. MATERIALS AND METHODS: Totally 188 cycles of blastocyst transfer were analyzed. Single blastocyst transfers were 55 cycles and double blastocysts transfers were 133 cycles. The rates of clinical pregnancy, implantation, multiple pregnancy, and miscarriage were compared. These comparisons were also performed in the following age groups; less than 29 years old, 30∼34 years old, 35∼39 years old. Furthermore, pregnancy and implantation rates according to the quality of blastocyst were analyzed. RESULTS: The rates of pregnancy and implantation in single blastocyst transfer were not different from those in double blastocysts transfer. However, multiple pregnancy rate in single blastocyst transfer was significantly lower than that in double blastocysts transfer. The miscarriage rate in single blastocyst transfer was significantly lower than that in double blastocysts transfer. In the age group of 35∼39 years old, pregnancy rate in double blastocysts transfer was significantly higher than that in single transfer. Transfer of high quality blastocyst achieved higher pregnancy rates in double blastocysts transfer compared to single blastocyst transfer in the same age group. CONCLUSIONS: Pregnancy rate in single blastocyst transfer was identical to that in double blastocysts transfer. However, multiple pregnancy rate in single blastocyst transfer was minimized compared to double blastocysts transfer. In age group of 35∼39 years old, pregnancy rate in double blastocysts transfer was significantly higher than that in single blastocyst transfer. The present study suggested two conclusions. Single blastocyst transfer is able to minimize multiple pregnancy rate without hindering pregnancy rate in the age group of 34 years or younger. Double blastocysts transfer could not be abandoned to achieve high pregnancy rate in the age group of 35 years or older.