Prenatal diagnosis of fetal chromosomal abnormalities
is the most common indication for invasive prenatal
testing. The prevalence of chromosomal abnormalities in
clinically recognized early pregnancy loss is greater than
50%. Fetuses with aneuploidy account for 6-11% of all
stillbirths and neonatal deaths. Chromosomal abnormalities
that are compatible with life but cause considerable
morbidity occur in 0.65% of newborns