Mental retardation factors are more, as follows: 1, is a developmental problem, mostly seen in intrauterine growth retardation; 2, genetic problems, such as some genetic diseases, such as trisomy 21, phenylketonuria such diseases, inherited metabolic diseases can cause mental retardation, if the mother suffers from disease, poor placental function, intrauterine infection, these problems can lead to fetal mental retardation; 3, birth asphyxia The child’s intelligence can also be affected if the child is abandoned, if the child is not cared for by adults, if there is no language environment, or if the parents give the child insufficient care stimulation.