Prenatal diagnosis for pregnancies at increased risk for chromosome abnormalities is routinely undertaken by karyotype analysis. While karyotype analysis remains the standard method to detect structural and copy number changes of chromosomes, it requires prolonged cell culture resulting in average reporting times of about two weeks. To relieve parental anxiety, and improve the quality and plasticity of pregnancy management, rapid methods, such as FISH and QF-PCR have recently been developed. These procedures are capable of detecting > 70% of chromosome abnormalities, and deliver a reliable diagnosis within 24 hours. Here we compare and discuss the advantages and limits of these rapid assays, and position them into a broader ethical context.