The efficacy of sequential day 3 embryo and blastocyst transfer in patients with repeated implantation failure

To evaluate the efficacy of sequential transfer that one cleavage-stage embryo on day 3 and one blastocyst on day 5 are sequentially transferred in the same treatment cycle over conventional day 3 embryo transfer and blastocyst transfer in patients with repeated implantation failure (RIF).

2836 frozen embryo transfer (FET) cycles in patients with RIF were divided into three groups according to female age: <35, 35-39 and >39 years old groups, and four groups depending on the number and period of embryo transferred: two day 3 embryo, two blastocyst, single blastocyst and sequential transfer groups; Pregnancy outcomes including implantation rate (IR), clinical pregnancy rate (CPR), abortion rate (AR), ectopic pregnancy rate (EPR), multiple pregnancy rate (MPR), live birth rate (LBR) and neonatal characteristics from all the groups were assessed.

Sequential transfer caused a significant increase in the IR, CPR and LBR over two day 3 embryo transfer and did not improve the IR, CPR and LBR over two blastocyst transfer in patients with RIF. Sequential transfer had higher CPR, MPR and LBR and lower IR than single blastocyst transfer. No significant differences were present in neonatal characteristics among the transfer protocol groups. Singleton group had a higher average gestational age and birthweight as well as a lower cesarean section rate, preterm labor rate and low birthweight rate than twin group. Additionally, the AR had no significant difference and the EPR of blastocyst transfer was low.

Sequential transfer was not an effective method to improve IR in patients with RIF, and blastocyst transfer with higher IR was suggested. Single blastocyst transfer could serve as an effective transfer protocol to reduce MPR.