Down’s is Down syndrome, a chromosomal abnormality also known as congenital dysmorphism or trisomy 21, which is a disorder caused by an abnormality of chromosome 21. A child with Down syndrome is called a Down’s child, also known as a Down’s baby. After birth, such babies usually have characteristic signs. The baby’s facial development is significantly different from normal babies, such as a widened distance between the eyes, a flattened nose, and a short and enlarged tongue. The baby’s palms often appear through the palm, with obvious mental retardation, physical development is significantly delayed, often combined with other developmental malformations, mid-pregnancy screening test for Down’s syndrome babies is called Down’s syndrome screening.