Babies like to sleep on their stomachs for a variety of reasons, including physiological factors and pathological factors (such as indigestion, upper respiratory tract infections) and so on. 1. Physiological factors: the baby in the womb most of the time for the prone position, after birth will also be used to sleep on their backs, contact with the bed surface area is larger, the sense of security may be stronger. 2. Pathological factors: (1) indigestion: if the baby has indigestion, especially at night before bedtime intake of too much food, resulting in abdominal distension, abdominal pain and other discomforts, the baby will also sleep on his stomach to promote the exhaust to relieve abdominal distension, abdominal pain and other discomforts. (2) upper respiratory tract infections: especially the phenomenon of the baby has a cold, there can be nasal congestion, runny nose and other phenomena, can block the respiratory tract, the baby sleeps on his stomach is more conducive to breathing, so the cold and nasal congestion can lead to the baby sleep on his stomach. Babies like to sleep on their stomachs when there may be other reasons, pay attention to observe whether the baby crying, mental anomalies and other phenomena, once the abnormalities, the need to go to the hospital in a timely manner, considering that some of the diseases caused.