A retrospective review of 100 consecutive pregnancies, involving 94 women receiving prenatal care at a rural western New York family practice, was conducted. Back pain was spontaneously reported to the physician by 23 women in 23 pregnancies. Eleven of the 23 women met diagnostic criteria for sacroiliac subluxation. These criteria include absence of lumbar spine and hip pathology, pain in the sacral region, asymmetrical movement of the posterior superior iliac spines upon forward flexion, a positive pelvic compression test and asymmetry of the anterior superior iliac spines. A cohort of 11 women meeting criteria for sacroiliac subluxation was treated with rotational manipulation of the sacroiliac joints. After manipulative therapy, 10 of the 11 women (91%) had relief of pain and no longer exhibited signs of sacroiliac subluxation.