Preterm Children Born Small for Gestational Age are at Risk for Low Adult Bone Mass
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Cross-sectional studies suggest that premature birth and low birth weight may both be associated with low peak bone mass. We followed bone traits in preterm individuals and controls for 27 years and examined the effects of birth weight relative to gestational age [stratified as small for gestational age (SGA) or appropriate for gestational (AGA)] on adult bone mineral density (BMD). We measured distal forearm BMC (g/cm) and BMD (g/cm2) with single-photon absorptiometry (SPA) in 46 preterm children (31 AGA and 15 SGA) at mean age 10.1 years (range 4–16) and in 84 healthy age-matched children. The measurements were repeated 27 years later with the same SPA apparatus but then also with dual energy absorptiometry and peripheral computed tomography (pQCT). Preterm individuals were shorter (p = 0.03) in adulthood than controls. Preterm AGA individuals had similar BMC and BMD height-adjusted Z-scores in adulthood compared to controls. Preterm SGA individuals had lower distal forearm BMC and BMD height-adjusted Z-scores in adulthood than both controls and preterm AGA individuals. Preterm SGA individuals had lower gain from childhood to adulthood in distal forearm BMC height-adjusted Z-scores than controls (p = 0.03). The deficits in preterm SGA individuals in adulthood were also captured by DEXA in height-adjusted femoral neck (FN) BMC Z-score and height-adjusted FN BMD Z-score and by pQCT in tibial cross-sectional area (CSA) Z-score and stress strain index (SSI) Z-score, where all measurements were lower than controls (all p values <0.05). Preterm SGA individuals are at increased risk of reaching low adult bone mass, at least partly due to a deficit in the accrual of bone mineral during growth. In our cohort, we were unable to find a similar risk in preterm AGA individuals.
KeywordsPeak bone mass BMD Preterm Small for gestational age Appropriate for gestational age Growth
Financial support was received from the Swedish Society of Medicine, Skåne University Hospital, and the Österlund, Pahlsson and Kocks Foundations.
Compliance with Ethical Standards
The authors have no financial relationships relevant to this article to disclose.
Conflict of Interest
Christian Buttazzoni, Björn Rosengren, Magnus Tveit, Lennart Landin, Jan-Åke Nilsson and Magnus Karlsson have no conflict of interest to disclose.
Human and Animal Rights and Informed Consent
All procedures performed in this study was approved by the Ethics Committee of Lund University and were in accordance with the 1964 Helsinki declaration and its later amendments.
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