The belly is very big when you are only 1 month pregnant, which is often caused by the following reasons in clinic: 1. After pregnancy, if you give sufficient reinforcement in nutrition and eat relatively more, there will be over-nutrition and accumulation of fat, and since the skin of the abdominal wall is relatively loose, the fat is easy to accumulate in the abdomen, which will make the abdomen look bigger. 2. If you are pregnant with twins or more than one child, the uterus will be much bigger than that of a single child pregnancy. 3. to be much enlarged, so the belly will also be big in this case.3, because of the cause of gravidity, if it is gravid, the uterus is enlarged very obviously, it will also appear this situation, it is recommended that you can distinguish it by ultrasound examination. In addition, if the abdomen is enlarged due to the accumulation of fat in the abdominal wall, it is recommended to just have balanced nutrition during pregnancy.