3Pope C S,Cook E K,Arny M,et al. Influence of embryotransfer depth on in vitro fertilization and embryo transferoutcomes[J]. Fertil Steril,2004,81( 1) : 51-58.
4Ishihara O,Kuwahara A,Saitoh H. Frozen-thawed blas-tocyst transfer reduces ectopic pregnancy risk: an analysisof single embryo transfer cycles in Japan[J]. Fertil Steril,2011,95( 6) : 1966-1969.