Five months baby always like to sleep on their stomach may be psychological factors, temperature discomfort, abdominal discomfort and other reasons. 1. psychological factors: five months baby always like to sleep on their stomachs, may be sleeping on their stomachs, the body curled up, more have to feel safe, sleep more solid. 2. Temperature discomfort: if the baby sleeps, the environment temperature is too cold, in order to reduce heat loss, may appear five months baby always like to sleep on their backs. 3. abdominal discomfort: such as the existence of abdominal pain, abdominal distension and other discomfort symptoms, may also lead to the emergence of five months baby always like to sleep on their backs, mostly due to sleep on their backs, the baby discomfort symptoms can be alleviated. Five months baby always like to sleep on their stomachs, there may be other reasons, it is recommended to go to the hospital in time to improve the examination to clarify the cause, under the guidance of the doctor to give targeted treatment or treatment.