According to Donum Vitae: For prenatal diagnosis makes it possible to know the condition of the embryo and of the fetus when still in the mother’s womb. It permits, or makes it possible to anticipate earlier and more effectively, certain therapeutic, medical or surgical procedures. Such diagnosis is permissible, with the consent of the parents after they have been adequately informed, if the methods employed safeguard the life and integrity of the embryo and the mother, without subjecting them to disproportionate risks.
But this diagnosis is gravely opposed to the moral law when it is done with the thought of possibly inducing an abortion depending upon the results: a diagnosis which shows the existence of a malformation or a hereditary illness must not be the equivalent of a death-sentence. Thus a woman would be committing a gravely illicit act if she were to request such a diagnosis with the deliberate intention of having an abortion should the results confirm the existence of a malformation or abnormality. The spouse or relatives or anyone else would similarly be acting in a manner contrary to the moral law if they were to counsel or impose such a diagnostic procedure on the expectant mother with the same intention of possibly proceeding to an abortion. So too the specialist would be guilty of illicit collaboration if, in conducting the diagnosis and in communicating its results, he were deliberately to contribute to establishing or favoring a link between prenatal diagnosis and abortion. In conclusion, any directive or program of the civil and health authorities or of scientific organizations which in any way were to favor a link between prenatal diagnosis and abortion, or which were to go as far as directly to induce expectant mothers to submit to prenatal diagnosis planned for the purpose of eliminating fetuses which are affected by malformations or which are carriers of hereditary illness, is to be condemned as a violation of the unborn child’s right to life and as an abuse of the prior rights and duties of the spouses.
Congregation for the Doctrine of the Faith, Instruction on Respect For Human Life In Its Origin And On The Dignity Pf Procreation Replies To Certain Questions Of The Day, #2.