Down’s syndrome, also known as congenital stupidity or trisomy 21, is caused by structural aberrations of chromosome 21 and is also associated with older pregnancies and aging of the eggs. Children with Down’s syndrome have distinctive facial features: small head circumference, flattened occipital region, short anterior and posterior diameters, short neck, wide distance between eyes, small eye fissures, low and flat nasal bridge, lateral upward sloping eyes, small ears, fat tongue, often sticking out of the mouth, salivation, these children generally have delayed development, bone age lags behind the age, short stature, short limbs, ligamentous laxity may make the joints overflexed. The child’s mental retardation becomes more pronounced with age, and motor and sexual development are delayed. Because of their low immune function, children are prone to various types of infections and are 10 to 30 times more likely to develop leukemia, often with congenital heart disease. There is no good treatment for Down’s syndrome, but prenatal screening is an effective measure to prevent the birth of children with Down’s syndrome. When couples of advanced maternal age or those who have a history of having abnormal children give birth again, it is recommended that prenatal screening be done carefully to prevent the birth of children with Down’s syndrome to the maximum extent possible.