The causes of pigeon chest in children mainly include two aspects, one is congenital and the other is acquired. Among them, congenital pigeon chest and funnel chest both involve hereditary factors. Additionally, if the central attachment point of the diaphragm in a child is underdeveloped, it can also cause pigeon chest, which is also a congenital cause.

Moreover, the acquired causes mainly include malnutrition and some specific thoracic diseases. Malnutrition is often related to rickets. Acquired thoracic diseases involve some diseases of the thoracic cavity, for example, pyothorax leading to flat chest, chest wall deformity, as well as some congenital heart diseases, heart enlargement, which then compresses the sternum causing it.