Nine-month-old baby sleeps on his back, considerations related to sleep habits, but also may be the emergence of indigestion and other conditions. 1. Sleeping habits, the baby in the mother’s womb have been in a state of curled up, after birth due to the lack of security may appear baby sleeping on his back symptoms, but also with the usual sleeping habits. 2. indigestion, if the baby has indigestion, digestive tract flatulence may lead to the baby discomfort, sleep on the stomach can be appropriate to alleviate the symptoms, so the baby usually like to sleep on the stomach. Nine-month-old baby sleeping on his back, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.