i think the main screen methods for pregnant woman for example in down sydrome are the triple or quadruple test, with the combination of routine test like nuchal translucency. As they screen non-invasive and do not carry a risk. Cvs is a diagnostic test offered to mothers who want to know for sure and is not recommended to those who want to progress with the pregnancy. Due to the infection and miscarriage risk being so high I don't think if will be a good 'screening test' . If offered to all pregnant women it will cause 14000 miscarriages al and 35000 infections
