It is possible to experience stomach pain before the physiological period, and the specific causes include physiological factors, pelvic inflammatory disease, endometriosis and so on. It is recommended to consult a doctor in time to find out the cause and treat it under the doctor’s guidance. 1. Physiological factors: before the onset of physiological period, patients may have a slight swelling and pain in the lower abdomen, mainly because the pelvis is in a state of congestion before the onset of menstruation, which will produce the corresponding abdominal area discomfort symptoms. 2. Pelvic inflammatory disease: chronic pelvic inflammatory disease patients in the physiological period before the onset of the phenomenon of pain, because the patient before the pelvic cavity is already in a state of congestion, physiological period to aggravate the phenomenon of congestion, and at the same time may aggravate the inflammation, so there will be symptoms of increased pain. 3. Endometriosis: If the patient is found to have pain in a fixed part of the pelvis in the corresponding specialized examination, and at the same time, a tender nodule is felt in the palpation, which highly suggests that he or she suffers from endometriosis, and it is recommended that the patient undergoes further examination such as ultrasound to confirm the diagnosis. There may also be other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy.