The main reason for a newborn baby to cry is to open the alveoli and help the baby breathe normally. Babies generally do not need to rely on the lungs to breathe in the womb, the alveoli are closed, but after birth babies need to breathe on their own, relying on the lungs to inhale oxygen and expel carbon dioxide, the newborn baby to let the baby cry, can open the alveoli, so that the lungs function normally. If the baby does not cry at birth and the alveoli are not opened, it may cause suffocation or even death of the baby and other serious consequences. Therefore, if a newborn baby does not cry, the doctor will usually tap the baby’s feet and other measures to stimulate the child to cry, which will allow the alveoli to open for normal breathing.