Effects of prematurity, intrauterine growth status, and early dexamethasone treatment on postnatal bone mineralisation

Aim-To examine the hypothesis that, apart from prematurity, intrauterine gr owth status (expressed as gestational age specific birth weight standard de viation scores), neonatal factors, and duration of dexamethasone treatment influence bone mineralisation in early infancy. Methods-In this prospective study, groups consisted of 15 preterm small for gestational age infants (SGA group) and 43 preterm appropriate for gestati onal age infants (AGA group). A reference group contained 17 term infants. Body size is known to affect bone mineral content (BMC), therefore postnata l bone mineralisation was measured when the study infants and controls had attained a similar body size. Bone mineral density (BMD) and BMC were deter mined by dual energy x ray absorptiometer of the lumbar spine (L2-L4). Results-Both preterm groups had significantly lower BMC and BMD than the we ight matched term reference group, but no difference was found in BMC and B MD between preterm SGA and AGA infants. In stepwise regression analysis, bo ne area, duration of dexamethasone treatment, weight at examination, and we ight gain per week were the most significant factors, explaining 54% of the variance of the BMC values. Conclusion-In particular, weight at examination, prematurity, and possibly dexamethasone treatment, but not intrauterine growth status, affect postnat al bone mineralisation.