A newborn baby with a small hole in the heart is considered to have an undescended foramen ovale. Babies with patent foramen ovale do not show any symptoms and usually do not need treatment. The foramen ovale is mostly located on the septum of the right and left atria, which is the transportation between fetal blood circulation and maternal blood circulation. Umbilical vein blood from the mother during the fetal period flows through this channel from the fetal right atrium to the left atrium and then to the whole body of the newborn, providing oxygen and nutrients to ensure normal growth and development. After birth, when spontaneous breathing is established and normal pulmonary circulation is established, the foramen ovale will slowly close in response to the increased pressure in the atria. Most newborns will close it within 24 hours after birth, completing the functional closure. Some babies will also close it at 5-7 months of age, and there are some children who will never close it. However, the foramen ovale is usually small, averaging 4.9mm. Babies with an unclosed foramen ovale usually have no symptoms and can still grow up healthy. If the foramen ovale is not closed, it is recommended that the child be admitted to the hospital for surgical treatment.