The umbilicus is the last part of the abdominal cavity to close, where the fetal umbilical cord is located, and is the weakest part of the abdominal wall.
The umbilical ring wraps around the umbilicus. When the umbilical ring is large and the fibrous tissue is not tough enough when the baby is born, the umbilical hernia is formed when the pressure in the abdominal cavity increases, such as when crying or coughing, and the intra-abdominal organs combined with the peritoneum pass through the space between the ligaments and protrude outside the umbilical ring.
Umbilical hernias in infants are generally harmless and tend to heal on their own as they get older. Umbilical hernias can also occur in adults, mostly due to acquired factors such as pregnancy, ascites, trauma etc. and require surgical intervention. Neonatal umbilical hernia (congenital umbilical hernia) is a special type due to a congenital developmental defect, which is more severe and often requires aggressive treatment.