The feeling of tightness in the stomach at 20 weeks of pregnancy is considered to be related to uterine contraction and enlargement of the uterus, or it may be due to factors such as abdominal muscle spasms. 1. Uterine contraction: Since the uterus will gradually become sensitive around the woman after pregnancy, it may cause uterine contraction when she is subjected to slight external stimulation or abdominal stimulation, which may lead to the phenomenon of 20 weeks pregnant tummy feeling tight. 2. Uterus enlargement: generally due to the woman during pregnancy, the fetus in the uterus gradually develops and shapes, the uterus will also be enlarged, the abdomen is passively pulled, the elastic fibers of the abdominal skin is damaged and broken, caused by the phenomenon of 20 weeks pregnant tummy feels tight. 3. Abdominal muscle spasms: It may be due to abdominal muscle spasms, which will cause the abdominal muscles to twitch, and then lead to the phenomenon of 20 weeks pregnant belly feeling tight. If the phenomenon of 20 weeks pregnant belly feels tight, you can go to the hospital in time to avoid delaying the condition and discomfort.