In some unfortunate circumstances, fetal disorders and diseases can complicate pregnancy. Prenatal diagnosis can be useful if it provides prospective parents time to adjust to and prepare for a child who may be born with developmental or functional challenges and disabilities. To assist them, clinical information about their fetus may be provided using prenatal diagnostic techniques if two conditions are met. The patient must give her free and informed consent to the procedure and the method(s) used must respect the life and integrity of the fetus. The information gained should be directed toward safeguarding the mother and fetus without subjecting them to disproportionate risks.

Background
Ethical and Religious Directives for Catholic Health Care Services, Fourth Edition. Directive 54.
Congregation for the Doctrine of the Faith, “Instruction on Respect for Human Life in its Origin and on the Dignity of Procreation” (Feb. 22, 1987) Origins 16: no. 40, Mar. 19, 1987, p. 702.