Babies can sleep in supine, lateral or even prone position. When babies are breastfed within half an hour, the lateral position is preferred because they are prone to spillage or vomiting within half an hour, and vomitus can flow out of the mouth in the lateral position to avoid suffocation. When the baby is within 3-4 months of age, the head shape is easily changed by the sleeping position, so if the baby has a flat head, tilted head and boat-shaped head and other deformities, it is necessary to go to the hospital to see a doctor to give guidance on sleeping position, to change the normal function of the head and neck, so how to sleep depends on the specific situation of the baby.