L as laws governing the transmission of hereditary characters are and will always be the same, but every day new mechanisms are developed to make human reproduction process safer. Among these novel possibilities, the one that allows us to know if baby information will be born with Down syndrome, hemophilia or other chromosomal alterations stands out.
We are not referring to the one that for several years has been operating under the name of amniocentesis, which consists of studying a sample of amniotic fluid from the pregnant woman, but to what is known as preimplantation genetic diagnosis, with which it is possible to detect diseases genetics before a new beginning to develop within the womb.
What does DGP consist of?
Preimplantation genetic diagnosis or PGD allows differentiating a healthy embryo from an altered one from a genetic point of view. It is based on the assisted reproduction technique known as in vitro fertilization, which, in turn, consists of the fertilization of an egg by a sperm in the laboratory.
When the ovum is fertilized, an embryo is produced, which then, when transferred to the maternal uterus, continues its development until it becomes a baby. Only through in vitro fertilization can the reproduction specialist have access to a cell that reflects the health of the embryo from which it has been removed.
Now, all the patients who resort to laboratory fertilization undergo pharmacological treatment so that several eggs mature, then they are aspirated – through a procedure called transvaginal puncture – and are put in contact with sperm from the Dad, so that not only one, but several eggs can be fertilized.
Once several embryos have been produced, it is possible to analyze each one to distinguish which one, due to its genetic integrity, is suitable, or not, for pregnancy. The cells are extracted from the embryos on the third day of their development in the laboratory, without causing any damage so that they can continue their cell division process.
In which cases is it indicated?
- Couples whose members have a sex-related disease, such as hemophilia – an inherited disorder that affects blood clotting in men.
- Women 38 years or older.
- Family history cases of Down syndrome or other genetic alterations.
- Women who have had two or more failed attempts at pregnancy due to IVF. When this happens, there is an error in the implantation of the embryo that can be detected before the transfer of the embryo to the uterus.
- Situations in which the male has altered semen, either in terms of shape, number or mobility of sperm.
- Cases in which the woman, regardless of her age, has aborted more than twice.
Of these circumstances, the age of the woman is one of the factors that must have more weight to opt for PGD, since, as Dr. Camargo explains, after 37 years of age, the risk of abortion due to problems of genetic type in the embryo. In a pregnant woman whose age is between 37 and 40 years, this risk is 17%, and between 41 and 43 years it rises to 38%.
It is necessary to remember that the age of the mother is also a very important factor in the incidence of babies with Down syndrome; after 37 years, the risk that the eggs will present genetic abnormalities is 65 percent. At 40 years of age, 70 percent of the eggs produced by a 40-year-old woman are genetically abnormal, while only between 3 and 5 percent of those produced at 43 are considered suitable for pregnancy.
Therefore, the probability of Down syndrome occurring in children of women over 40 is one for every 40 pregnancies. It is just for this reason that the older the woman, the ideal is to resort to genetic tests that allow her to know if her baby could be born with any genetic alteration.