A bulge on one side of the belly is not necessarily a contraction, but may also be a fetal limb. When a woman is in the middle or late stages of pregnancy, the fetus is not necessarily in the middle of the lower abdomen, but may have limbs or head on one side of the belly, and will present a bulge. If there is no tightening of the abdomen, the woman can also observe it first through proper bed rest to the other side, as long as the fetal movement is good and there is no frequent fetal movement. If a woman has tightening of the lower abdomen and stomach pain when one side is bulging, most of them are due to irregular contractions, so pay attention to proper rest and do not stand for a long time. If the pain is not relieved after rest, it is better to go to the hospital for gynecological ultrasound and fetal heart monitoring, and if there is preterm miscarriage, preterm labor or labor, timely hospitalization is needed.