Clinical outcome analysis of sequential transplantation of frozen-thawed embryo transfer cycle: a retrospective study

The sequential transplantation was a new mode of in vitro fertilization and embryo transfer. To compare the clinical outcomes of sequential transplantation, embryo transplantation and blastocyst transplantation during freeze-thaw embryo transfer cycle. The retrospective study was conducted on 767 patients who received freeze-thaw embryo transfer at Reproductive Medicine Center of Hangzhou Women Hospital from July 1, 2020 to June 30, 2021. According to the age of transplanted embryos, all patients were divided into sequential transplantation, embryo embryo transplantation group and blastocyst stage transplantation group. The clinical data, embryo status and pregnancy outcome of the 3 groups were compared, the number of transplanted embryos in the sequential group was significantly higher than that in the other 2 groups (P < .05). The implantation rate of blastocyst transplantation group was the highest, there was no statistical significance between the sequential transplantation group and the other 2 groups (39.13% vs 30.00%, 39.13 vs 43.50%). The multiple birth rate (30.77%) and spontaneous abortion rate (20.51%) were higher in the sequential transplantation group, and there was no significant difference among the 3 groups (P > .05). The sequential transplantation cycle can obtain a higher clinical pregnancy rate than the conventional single cycle transplantation, without causing the waste of transplanted embryos, and can be used as the choice mode of resuscitation transplantation cycle for some patients.