Pregnant women’s stomach suddenly became bigger may be reduced activity, hyperemesis gravidarum and other conditions, should promptly consult a doctor to find out the cause of the disease. 1. Reduced activity: After knowing that you are pregnant, your activity decreases, your metabolism slows down, and you strengthen your nutrition in your daily life. Eating relatively more will cause excess nutrition, which will lead to the accumulation of fat, and since the skin of the abdominal wall is relatively loose, fat will easily accumulate in the abdomen, which will result in the formation of a larger stomach. 2. Grape fetus: it may be caused by grape fetus, if it is grape fetus, the uterus will be much larger than the uterus of a normal pregnancy, so clinically there will be a bigger belly, it is recommended to do ultrasound examination as soon as possible. If you find that the pregnant woman’s stomach suddenly becomes bigger, it is recommended to consult a doctor in time, ask the doctor to clarify the cause of the disease and give targeted treatment.