There is no way to increase the likelihood of identical twins or to ensure that you will have two babies. However, it is possible to increase the chance of having twins by transferring two embryos. It is important to keep in mind that the risks are increased in this type of pregnancy, as there is a greater likelihood of maternal and foetal complications.
To choose the sex of the embryos, pre-implantation genetic diagnosis (PGD) would be necessary, but in Spain sex selection is only allowed for therapeutic purposes.
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