Stomach pain like menstrual cramps in 5 weeks of pregnancy may be uterine contraction pain, ectopic pregnancy, and preterm miscarriage. 1. Physiological conditions: Pregnant women may experience a series of reactions in the early stages of pregnancy, such as menopause, early pregnancy reaction, breast changes, etc. Some people may have uterine contraction pain without uterine bleeding. 2. Ectopic pregnancy: when the fertilized egg is deposited in a part of the uterus other than the body cavity, such as tubal pregnancy, with the gradual enlargement of the embryo in the fallopian tube, it can cause hidden pain or soreness in one side of the lower abdomen, and if the pregnancy is miscarried or ruptured, there will be pain in the lower abdomen. 3. Pre-eclampsia: a small amount of vaginal bleeding at 5 weeks of pregnancy, followed by paroxysmal lower abdominal pain or lower back pain, like dysmenorrhea. Early pregnant women with lower abdominal pain, need to promptly seek medical attention. According to the history, physical examination and related auxiliary examination such as ultrasound and other clear diagnosis, follow the doctor’s instructions for treatment.