Pregnancy-associated osteoporosis.

The clinical features, investigation and outcome in 24 patients with pregnancy-associated osteoporosis, followed for up to 24 years from the first pregnancy are described. Symptoms occurred most often in the first pregnancy (17 patients) at a mean age of 27 years (range 21-36); the most frequent was back pain in late pregnancy or post partum (n = 18); less common was hip (n = 5) or ankle (n = 1) pain. In most, symptoms improved soon after delivery. Four subjects had pre-existing disorders known to reduce bone density (corticosteroid therapy, heparin treatment, mild osteogenesis imperfecta and previous anorexia nervosa). Radiographs showed vertebral collapse or localized osteoporosis of the hip, with MRI evidence of oedema. Forearm bone mineral density (BMD) was sometimes normal, but spinal BMD (measured by DXA) was low. Bone biopsies in eleven patients showed features compatible with osteoblast failure. Except for the patient with mild osteogenesis imperfecta, cultured dermal fibroblasts synthesized and exported normal Type I collagen. In 14 subsequent pregnancies (10 patients) there was no recurrence in ten and mild symptoms in the remainder. Excluding one patient who had repeated osteoporotic fractures and vertebral collapse, the long-term prognosis was good.