The pain at the root of the thigh after childbirth may be caused by the following reasons: 1. It may be caused by fatigue of the muscles related to the pelvic floor, as seen in patients who overuse the muscles around the pelvic floor during childbirth, resulting in excessive fatigue of the muscles here and corresponding pain in the pelvic floor and the root of the thigh after childbirth. 2. It may be caused by aseptic inflammation here, as a result of excessive squeezing and stretching of the muscles during childbirth. The pain may be caused by infection in the surrounding area, which can be seen when the patient has a laceration in the birth canal or after a lateral incision, which causes pain in the whole perineum and the root of the thigh. 4. It may also be caused by skin lesions after delivery, because after delivery, there will be a lot of secretions here, plus the temperature here is relatively high, it may cause skin lesions like eczema or skin infections, causing pain in this area.