Preimplantation genetic diagnosis (PGD) is an assisted reproduction technique that allows the genetic characteristics of embryos to be studied before their transfer to the mother's uterus in order to avoid transmitting genetic diseases or chromosomal alterations.
It is usually recommended when there is a risk of transmitting a genetic disease to the offspring, if one member of the couple has an altered karyotype, in cases of repeated miscarriages, if several unsuccessful IVF cycles have been performed. It can also be indicated in cases of predisposition to cancer of genetic origin and in the case of monogenic diseases (those caused by an alteration in a specific gene).
If we are talking about PGD to confirm that the embryonic karyotype is normal (and not in all cases of diseases or genetic alterations already known), it is usually indicated from 38-39 years of age of the woman, which is when the prevalence of chromosomal alterations in the embryos generated begins to increase significantly. In this case, the probability of having chromosomally altered embryos is very high.
If the patient has a low ovarian reserve it is likely that she will not have many embryos suitable for PGD biopsy, so in each case it will be decided, together with the patient, if it is worth studying them or if this technique can be avoided, depending on her medical history and preferences.