The baby’s unstable vertical head at 4 months is an abnormality. At the age of March, the baby should have a stable vertical head, and the head can freely turn around following toys or people walking around. If the baby is still unstable at the age of 4 months, brain injury or genetic metabolic disease or genetic chromosomal disease should be considered, and the baby should be evaluated at the hospital in time, together with the presence of perinatal risk factors such as prematurity, hypoglycemia, nuclear jaundice, hypoxic-ischemic encephalopathy and low birth weight. If there are any of these medical histories and manifestations, you need to visit the child health department or rehabilitation department in time for early evaluation and early intervention, as the younger the age of starting intervention, the better the results.