Infants’ dyspnea lying flat on their backs may be caused by bronchial asthma, severe pneumonia and acute left heart failure. 1. Bronchial asthma: it usually causes babies to have dyspnea lying down with obvious symptoms such as coughing and wheezing, and some babies may have sweating and irritability. 2. Severe Pneumonia: Usually, children with severe pneumonia suffer from respiratory dysfunction of the lungs, resulting in babies lying down and breathing poorly. 3. Acute left heart failure: Children with sudden acute left heart failure due to various congenital heart diseases or myocarditis are usually accompanied by symptoms such as dyspnea, sedentary breathing, sweating and irritability. Babies lying down breathing, there may be other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.