Babies who are not full-term cannot raise their heads on their own, it is not recommended to lie on their stomachs, otherwise their bodies will be uncomfortable and even prone to suffocation and other situations. Not full-term baby can not move the body freely, and can not express their own feelings. If lying down for a long time, the center of gravity is concentrated in the chest and abdomen, the baby will be uncomfortable, and it is easy to make the airway blocked, so that suffocation occurs. Generally speaking, when the baby is born within three months, it is recommended that the baby lie down flat, and when there is the ability to raise the head on its own, it can choose other positions. If the baby appears to be lying on his back, parents should adjust the child’s position in time, and carefully watch the child to prevent breathing difficulties, spitting up or other accidents because of lying on his back.