What happened to the left lower abdominal pain at 31 weeks of pregnancy? At around 31 weeks, there are two cases of pain in the left lower abdomen of pregnant women: the first case is that the fetus is too big and presses the inferior vena cava, and then it presses the abdominal intestine, which slows down the peristalsis of the abdomen and causes pain in the left lower abdomen. In the second case, uterine contractions are possible and can be examined. Ultrasound can also be performed to exclude any other diseases, to exclude organic diseases, if there are no other problems, fetal movement of the fetus, can also cause pain in the lower abdomen. If the pain is obvious and cannot be relieved, hospital consultation is recommended, except for other diseases.