Prenatal diagnosis universalization allows knowing the prognostic possibilities in a situation of limited therapeutical resources. Therefore, besides permitting the peace of a normal fetal development, in other circumstances it can provoke parent's requirement to interrupt pregnancy in cases of malformation or chromosomal alteration, situations that parents may conceive as difficult for child's life and family environment. Diagnostic tests reliability and risks, information given to the parents, conversion in an eugenic practice of prenatal diagnosis and OMS recommendations in relation to the optional and voluntary character that this diagnosis should have are analysed.