Newborns are not recommended to lie on their backs, because the physiological curvature of the neck during the neonatal period has not yet formed, the neck muscles are not enough to support the newborn to lift the head. If the newborn sleeps on his stomach, because he can not adjust the position of the head, so it is very easy to cause the mouth and nose is pressed on the pillow caused by suffocation, the consequences are very serious. If parents want their newborn to lie on his or her stomach or back, there must be a parent on the side at all times to supervise, and once the mouth and nose are covered, immediately turn the newborn over and change positions. Even so, it is not recommended to let the newborn baby lying on his back for a long time. When 2-3 months of age, the baby can raise his head on his own, then parents can let him lie on his back, lying down, so as to exercise the strength of the neck muscles.