Hello Dimitar.

It would be more appropriate to select and transfer healthy good quality of embryos together through a single transfer. Consecutive transfer might disturb greatly the niche of the first embryo that has just adapted to new milieu of tracts due to the strained reproductive tracks or unnecessarily stimulated muscular contractions. Psychologically too, complete it in a single transfer. Do not believe what other clinics say. You cannot get scientifically sound data which is better.

Regards.

In this case I am talking about simultaneous transfer of two embryos (double ET). One of them is a cleavage stage embryo (Day-3) and the other one is a blastocyst (Day 5).In our clinic this approach gives significantly better results in comparison with the other types of double embryo-transfer (incl. consecutive ET).

The embryo age and the uterine lining should be synchronized to achieve best implantation. One day difference may not impact much but greater difference will impact implantation. It is based on the animal studies, however, in human, probably implantation window may be wider. You will be getting higher pregnancies if you are transferring , technically, 2 blastocysts on day-5, instead of transferring one day-3 and one day-5. I do not know how you will do transfer of one day-3 and one day-5 fresh embryo, unless you have day-3 cryopreserved embryo or have donated embryo.

In repeated failure, two transfers, one on day-3 and the other on day-5 in the same cycle has been done and is generally considered to increase chances of implantation. The idea is to catch the implantation window. We have had live birth from a similar case. Apparently, the second transfer does not affect the embryos transferred on day 3 as they have yet not implanted.