Down's screening takes months.

For every woman who has fertility requirements after pregnancy, it is normal to need regular prenatal check-ups and comprehensive examinations to determine the growth and development of embryos. The time for Down's screening is generally carried out around 4 months of pregnancy. It is normally suitable for women younger than 35 years old and pregnant with single births. If the woman is over 35 years old or pregnant with twins, then it is not possible to do Down's screening directly. Generally, non-invasive DNA or amniocentesis is required. And Down's screening in pregnancy 16 weeks examination, First to do B ultrasound, See fetal growth and development, Then according to the examination results are normal circumstances, Can draw blood to do Down's screening, Results more in half a month or so out.