In order for a twin pregnancy to occur by inseminating a woman, it is necessary that two eggs are expelled at ovulation. In addition, it is essential that both eggs are fertilised, that the two embryos generated develop to blastocyst and that they manage to implant in the patient's uterus.
In contrast, for a twin pregnancy, the embryo resulting from the fertilisation of one egg must be divided into two. In artificial insemination, the fact that the embryo fragments during its development does not seem to be increased, so the probability of identical twins can be considered the same as naturally.
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