Pregnant belly button bulging out may be a physiological phenomenon, may also be adults umbilical hernia and other causes. 1. physiological phenomenon: because with the increase in pregnancy weeks, the fetus in the uterine cavity gradually growth and development, indirectly on the uterus to cause a certain amount of pressure, and then the abdominal pressure also gradually rise, so some women pregnant navel will be convex, if there is no other discomfort, more than the consideration of a normal physiological phenomenon, do not have to worry about too much. 2. adult umbilical hernia: this disease occurs with obesity, multiple pregnancies, ascites, history of abdominal surgery, long-term peritoneal dialysis and other reasons, the typical symptom is the umbilicus soft bulge or protrusion, may be accompanied by dyspepsia, abdominal pain and other discomforts, if the umbilical hernia occurs incarcerated or strangulation, the patient will be vomiting, severe abdominal pain and other symptoms. If you are pregnant with a protruding navel to exclude the normal situation, you need to go to the hospital in time to improve a series of related examinations to clarify the specific causes.