13 weeks of pregnancy belongs to the middle of pregnancy, during this period, if there is a vague pain in the stomach, mostly seen in the following cases: 1, caused by contractions of the uterus, may be accompanied by lumbosacral discomfort, at the same time there will also be red phenomenon, belong to the pre-eclampsia miscarriage, need to apply under the guidance of the doctor to protect the fetus medication, bed rest, can not be strenuous activities, also can not have intercourse; 2, if the pain is in the upper abdomen, mostly seen because If the pain is in the upper abdomen, it is most often caused by poor gastrointestinal function, intestinal spasm or stomach cramps, this situation is related to diet, also seen in eating cold, spicy food stimulation caused. We should pay attention to avoid bad stimulation, diet is to be light, such as drinking porridge, eating noodles, when necessary, you can apply hot compresses on the upper abdomen, can relieve pain; 3, 13 weeks of pregnancy, the uterus began to slowly increase, ligament tension, so sometimes there may be lower abdominal pain, but this pain is often not regular, only occasionally feel some discomfort, more rest can be relieved.