The possible causes of bone pain under the lower abdomen include trauma, urinary tract disorders, and separation of the pubic symphysis. 1. Trauma: If there is a history of trauma or just after strenuous exercise, it is likely to be a local soft tissue injury, swelling, pain, serious cases lead to pelvic fracture, it is recommended that as soon as possible to perform imaging tests to clarify the condition. 2. Urinary system disorders: If accompanied by frequent urination, urinary urgency, urinary pain and other symptoms, it may be cystitis, prostatitis, pyelonephritis and other urinary system infections. 3. Separation of the pubic symphysis: If a woman in late pregnancy or just after giving birth experiences pain in the bones under the lower abdomen, it is considered separation of the pubic symphysis, which is a normal physiological phenomenon. There may be other reasons for the pain in the lower abdominal bone, it is recommended to go to the hospital as soon as possible for a detailed examination to clarify the cause of the disease and timely treatment.