SummaryThe problems of physical deformities and metabolic defects in the pregnant osteogenesis imperfecta patient are discussed. The benefit of epidural anaesthetic is stressed.Osteogenesis imperfecta (fragilitas ossium—the brittle bone disease) is a rare inherited and heterogeneous disorder with an incidence of 1 in 25000–30000 births (Graffeo et al., 1953). The main clinical feature of bone fragility may be slight or severe, producing a wide spectrum of disease.Other clinical manifestations include blue sclerae, early hearing loss, fragile teeth, lax joints and heart valve incompetence (Albright and Millar, 1981; Smith et al., 1983). The metabolic findings include decreased platelet aggregation, increased serum and urine inorganic pyrophosphate and increased metabolic rate, with hyperpyrexia under general anaesthesia (Roberts and Solomons, 1975). Biochemical studies show the disease arises from a variety of inborn errors of collagen synthesis.Two forms, congenita and tarda, are distinguished (Sillence et al., 1979). The congenital form is lethal, with death in utero or in the immediate neonatal period. Inheritance is by an autosomal recessive gene. Osteogenesis imperfecta tarda is transmitted by an autosomal dominant gene with highly variable penetrance and expression.