About umbilical hernia. An umbilical hernia is a result of weakness in the muscles in or around your belly button. It causes the belly button to pop outwards and can happen at any age. Umbilical hernias are most common in women during and after pregnancy, and in people who are overweight.bout umbilical hernia. An umbilical hernia is a result of weakness in the muscles in or around your belly button. It causes the belly button to pop outwards and can happen at any age. Umbilical hernias are most common in women during and after pregnancy, and in people who are overweight.