Nowadays the trend is to do the embryo transfer on day 5, this has its advantages. Leaving the embryo in culture until day 5 we can follow all its progress and see if it develops favourably. So we can choose the best embryo, since many times we see embryos with good quality on day 3, but sometimes these do not reach the stage of the blastocyst. In this way, we make sure to choose the best embryo morphologically and that has been able to form a blastocyst. In this case, the transfer of a single blastocyst is recommended, avoiding transfers of more than one embryo on day 3. According to recent studies, the rate of live birth is higher in transfers on day 5 than on day 3.