In the Netherlands prenatal diagnosis after screening for chromosomal abnormalities is done by karyotyping and is restricted to pregnant women with an increased risk of a child with trisomy 21, 18 or 13. However, karyotyping will detect a wider range of chromosomal abnormalities. Replacing karyotyping by rapid aneuploidy diagnosis (RAD) - a test with a more narrow scope - is currently under discussion. A possible drawback of RAD is that some rare but clinically relevant abnormalities may be missed. A possible advantage is that pregnant women will not be confronted with outcomes that the screening was not initially directed at. Each delineation of the scope of prenatal testing implies a normative choice that requires justification. Moral principles can be invoked for both narrowing down and further broadening of the scope of testing.