6-month-old babies with mental retardation may have difficulty in feeding and easy choking, abnormal crying, clumsy movements, poor response to sound, etc. 1. Difficulty in breastfeeding and easy choking: 6-month-old babies with mental retardation may show poor coordination in sucking and swallowing, which is usually manifested as difficulty in breastfeeding and easy choking. 2. Abnormal crying: if the baby is stimulated, it is easy to cry for a long time, and some of the affected children may have sharp or even feeble cries after repeated stimulation or continuous stimulation. 3. Clumsy movements: 6-month-old babies with mental retardation may show slow reaction and uncoordinated movements. In addition, the baby is unable to gaze at slow-moving objects or turn his/her head towards the source of sound. 4. Poor response to sound: Generally babies with mental retardation have poor response to external sounds and cannot give timely feedback when their relatives make sounds. In addition to the above abnormal symptoms, babies may also have other manifestations such as delayed motor development and abnormal muscle tone. Parents should pay attention to these abnormal symptoms and go to the hospital in time to get a clear picture of the cause and follow the doctor’s instructions for treatment.