Bone mineral density in school age infants born preterm

Background: The age at which children born preterm normalize their bone mineral density, is not well known. Aim: To study if children born preterm have normalized their bone mineral density at age 5 to 7 years. Patients and methods: Twenty six infants born preterm (14 male), were studied at age 5 to 7 years. Birth weight, present weight and height, bone age, calcium and phosphate intake (it the first year of life and at the current age were assessed. Bone mineral density was measured by single photon X ray absorptiometry in the dominant forearm. A blood sample was obtained to measure, insulin growth factor 1 (IGF-1). As a control group, 105 healthy age-paired infants born at term, were studied. Results; Bone mineral density was significantly lower in infants born preterm than in their term counterparts (0.273+/-0.01 g/cm(2) and 0.302+/-0.01 g/cm(2) respectively, p <0.001). There was a positive correlation between bone mineral density and IGF-1 (r=0.49, p=0.01.). No correlation with the other measured parameters was observed. Conclusions: Infants that were born preterm have a lower bone mineral density at 5 to 7 years of age than their term controls. Bone mineral density correlates with IGF-1.