Q: My baby’s navel is bulging outward and becomes bigger and harder when he cries, but it can become smaller and softer when it is quiet or when I press it with my hand. A: This condition is clinically known as an umbilical hernia. Umbilical hernia is an extra-abdominal hernia in which the contents of the abdominal cavity protrude from a weak defect in the umbilicus, and is the collective name for extra-abdominal hernia occurring in the umbilicus. The umbilicus is the latest part of the abdominal wall to close during embryonic development. After the umbilical cord is shed, the newborn baby’s abdominal muscles on both sides do not completely come together, leaving a defect in the umbilicus and a lack of fatty tissue, while the outermost layer of the abdominal wall, skin, fascia and peritoneum, are directly connected together and become a congenital weak spot. When the pressure in the abdominal cavity is increased due to crying, coughing, defecation, etc., the abdominal viscera, especially the small intestine, together with the peritoneum, will gradually eject outward from the umbilicus, forming an umbilical hernia. Most umbilical hernias within 1 cm of the umbilical ring defect can heal spontaneously before the age of 2 years and do not require special treatment. Some parents hope to take compression measures such as homemade cloth belts to try to block the outward expansion of the umbilical hernia swelling, but they basically cannot achieve control. Doctor’s tip: As children grow and develop, their abdominal wall muscles develop with them, and the umbilical ring can gradually shrink until the umbilical hernia eventually disappears. Therefore, for most children with umbilical hernia under one year of age, most doctors will recommend withholding treatment. When the child reaches 3 months of age, the unprovoked crying will be reduced and the hernia will gradually heal itself. Even in older children with umbilical hernias that remain untreated, the umbilical ring can usually be repaired at the hospital after the age of 3 years. It is important to emphasize that each child’s situation is different, and whether and when treatment is needed will depend on the child’s condition.