: Does embryo transfer day (D5 vs D3) affect cumulative live-birth-rates (CLBR), time to live-birth (TTL) and cost-per-live-birth
(CPL) in recipients of donated oocytes?
: This is a single center RCT conducted between April 2017-August 2018. The recipients
of donated oocytes were randomized to cleavage stage (D3 Group) or to blastocyst stage
(D5 Group) embryo transfer.
Eligible women were recipients between 18-50 years, in their 1st/2nd synchronous cycle (excluding: PGT-A, recurrent implantation failure and biopsy obtained
sperm). Primary outcome was CLBR, within 12 months from 1st embryo transfer, considering fresh and subsequent frozen transfers. Additionally,
we analyzed TTL (time from 1st embryo transfer until 1st livebirth) and CPL (cost per-live-birth).
: A total of 134 recipients were randomized to D3 Group (n=69) or to D5 Group (n=65).
D5 transfer results in 15.9% relative increase in CLBR and a significant shorter TTL
as compared with D3 transfer. To reach a 50% CLBR, D3 Group required 6 months more
than D5 Group (15.3 vs. 8.9 months, respectively). Moreover, the average CPL in D3
strategy supposed an increase of 24% with respect to the D5 strategy (14817.1 euros
vs 10959.2 euros). Furthermore, clinical pregnancy rate (CPR) was approximately 25%
inferior in D3 Group. The trial was prematurely stopped after unplanned interim analysis
due to the initial poor results in D3 arm.
: The present study provides evidence that the transfer of blastocyst stage embryos
in recipients of donated oocytes should be preferred since it leads to higher clinical
pregnancy rate, live birth rate, shorter time to pregnancy and lower costs to achieve
the pregnancy, as compared to cleavage stage embryo transfer.