One reason is that babies unfortunately inherited the bad genes of the previous generation. Some data show that the possibility of mental illness or mental retardation among family members is much higher than that of couples without family history, which makes mental retardation appear family aggregation. There are also couples who have no patients at home, but because of smoking and drinking, the genetic variation of eggs or sperm has also led to the birth of mentally retarded babies.
Another reason is that the baby was stimulated by bad environment during the fetal period, such as rays, electromagnetic waves, air polluted by cadmium and so on. , affecting the differentiation and development of the baby's nervous system, or inducing the baby's chromosome mutation, leading to the baby's mental retardation.
Another reason is that pregnant women are infected with certain diseases during pregnancy, such as rubella virus and cytomegalovirus, which affects the development of the fetus in the uterus, especially the development of the brain, causing irreversible damage to the nervous system of the baby and affecting intelligence.
The last important reason is that the mother is undernourished during pregnancy, which leads to the undernutrition of the baby, which affects the development of its nerve cells and leads to the baby's dullness and stupidity.
In addition, if the baby causes intracranial hemorrhage and severe asphyxia at birth, it will also bring irreparable damage to the baby's brain development. Therefore, it is an important measure to publicize the knowledge of eugenics and do a good job in perinatal care to prevent mentally retarded babies from being born.