Professionals working in assisted reproduction aspire to 100% efficiency for every treatment and this is becoming increasingly feasible thanks to new research lines, cutting edge technology and innovative techniques such as blastocyst (the name for embryos at day 5) transfer.

With that in mind, how can we explain the fact that according to the latest SEF (Spanish Fertility Society) records almost 70% of embryos are transferred either on or before day 3?

Two key benefits of blastocyst transfer

There are many benefits to transferring embryos at the blastocyst stage, although two main ones. Transferring embryos on day 5 increases the treatment’s success rate; according to the SEF there is a 17% increase in successful pregnancies and a 15% increase in live births.

The second main benefit is the response that has been found to one of assisted reproduction’s main challenges, namely a reduction in the number of multiple births. In IVF Donostia we are clear that these kinds of high-risk pregnancies are avoidable when this technique is used.

60% of the multiple births we see today are a result of assisted reproduction. Hardly accidental when you consider that according to latest SEF figures 65.8% of transfers recorded were of two or more embryos.


No of IVF embryo transfers0A2015 SEF Data

Although assisted reproduction multiple births have decreased by 27% in 2015 they still accounted for 20% of all births. This is a relevant figure if we consider the risks involved in carrying more than one baby to term.

Dr. Estafanía Rodríguez and Dr. Elisa Pérez, expert gynaecologists in assisted reproduction agree on this. “The main risk of multiple births is prematurity. The probably of giving birth between week 33 and week 36 (i.e. a premature birth) is 36.5% in twin deliveries. And there are additional risks both for mother and neonate, so everything in our power should be done to avoid these kinds of pregnancies.

With only a 1.4% change of carrying twins, quite obviously the most recommendable option is single embryo transfer at blastocyst stage. Dr Elisa Pérez adds, “Sometimes it is difficult to make patients understand that transferring more than one embryo does not lead to a higher chance of implantation. In fact in the case of embryos, less is definitely more: we should assess quality rather than quantity”.

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