Pelvic insufficiency during pregnancy, pelvic girdle relaxation, is defined as a condition with pain at the pubic symphysis and/or the sacroiliac joint developing in connection with pregnancy or delivery. No unambiguous criteria for the diagnosis of pelvic girdle relaxation exist but the following findings occur: Direct tenderness at the pubic symphysis and/or sacroiliac joint, waddling gait, pain on change of position, positive Trendelenburg's sign, iliac compression test, iliac gapping test and sacral pressure test. The frequency is 7.6-18.5 per 1000 deliveries. The incidence is increased in multiparae and women with occupations which strain the back. Recurrence occurs in 41-77%. The condition appears for the first time usually in the 5th-8th months of pregnancy. The majority of patients recover shortly after delivery but in some a condition of prolonged pain persists. The cause of pelvic girdle relaxation is unknown. Hormonal and biomechanical factors are considered to be of significance. No increased mobility in the pelvic joints nor general hypermobility have been demonstrated. Treatment is symptomatic and consists of information, instruction in relief and psychosocial support. Exercises and a trochanter belt may be useful. No controlled investigations of the value of treatment are available.