Early symptoms of mentally retarded infants mainly include difficulty in breastfeeding, abnormal face and seldom crying, which are analyzed as follows: 1. Difficulty in breastfeeding: infants have difficulty in feeding, can’t suck the nipple, easily choke and spit up, etc., which may be related to the damage of the nervous system. 2. Abnormal face: Some children with congenital mental retardation will have abnormal face, such as crooked and slanted eyes, wide eye spacing, and large head circumference. 3. Rarely cries: If the child rarely cries, stimulates the child to not cry, indifferent to the surrounding environment are not normal. There may be other symptoms of infantile mental retardation, so it is recommended to take your child to the hospital for relevant tests to more accurately determine whether there is any abnormality.