1.When caring for the baby, the arms and legs often “jerk”, as if “very strong”, and feel resistance when moving or very soft like a “rag doll”; 2.After the first month, the head is always tilted back, can not sit upright when holding 3. 3 months old cannot lift the head, cannot laugh or pronounce words; 4. 4 months old hand still clenches the fist and does not release, thumb is close to the palm; 5. 5 months old forearm cannot support the body when lying prone; 6. 6 months old pointed foot when standing, heel can not hit the ground, can not reach out to grasp things; 7. 7 months old can not pronounce ba, ma; 8. 8 months old can not sit alone; 9. 9, head and hand shake frequently; 10. 10.Crying all day or excessively quiet, feeding difficulties. If parents find that the infant has one of the above elements, they should go to a qualified health care unit for further examination.