During gestation, the umbilical cord passes through a small opening in the baby’s abdominal muscles. The opening normally closes just after birth. If the muscles don’t join together completely in the midline of the abdominal wall, an umbilical hernia may appear at birth or later in life.
In adults, too much abdominal pressure contributes to umbilical hernias. Causes of increased pressure in the abdomen include:
• Multiple pregnancies
• Fluid in the abdominal cavity
• Previous abdominal surgery
• Long-term peritoneal dialysis to treat kidney failure