"Four concave signs" after birth

Children with congenital laryngeal atresia have no breathing and crying after birth, showing "four concave signs", but no air inhalation. During the embryonic stage, the larynx is not formed due to the blocked larynx development, and the larynx is not ventilated at birth, which is called congenital larynx. There are two types of membrane or cartilage. Regardless of any atresia, there is often a small hole in the back of the throat called a pharyngotracheal tube. Because the development of the larynx is blocked during the embryonic period, the larynx is not formed, and the larynx is blocked from ventilation at birth.