Mild stenosis of the pulmonary valve in 4-month-old babies if there are no obvious symptoms do not need special treatment, to maintain follow-up can be, if there is a slight phenomenon of breathlessness, you can also consider through the inhalation of oxygen and other ways to relieve. Mild pulmonary stenosis generally does not have a significant impact on the health of 4-month-old babies, the child if there are no obvious symptoms of discomfort, generally do not recommend targeted treatment, strengthen the observation can be. If the child has severe stenosis of the pulmonary valve, resulting in serious discomfort such as restricted physical activity, surgery can be considered. Children with mild stenosis of the pulmonary valve should go to the hospital for regular checkups. Once children are found to have symptoms such as breathlessness and shortness of breath after activity, they should seek medical treatment immediately to avoid delaying their condition.