Blastocyst Culture and transfer is one technique under which the embryo is processed in the laboratory for 4-6 days after fertilisation before being placed in the womb. The embryo is made of number of cells as a result of being processed for so many days. For instance, an embryo developed within 4-6 days is more advanced than that produced within three days. These type of embryos are called blastocysts. The advantages of blastocyst culture and transfer is that it reduces the chance of multiple pregnancies. Also the implantation and pregnancy rate is more successful.