When to screen for Down syndrome Down syndrome is a common chromosomal disorder that affects the normal development of babies. In order to identify pregnant women with Down syndrome as early as possible, Down syndrome screening is essential. So, when and how should Down syndrome screening be carried out during pregnancy? This article will introduce information related to Down syndrome screening from four aspects. 1. Down syndrome screening time Down syndrome screening is usually performed around the 13th to 14th week of pregnancy, and the 15th to 20th week is also a more appropriate time range. Generally speaking, if the pregnancy is more than 20 weeks, Down syndrome