Striking differences in estimates of infant adiposity by new and old DXA software, PEAPOD and skin‐folds at 2 weeks and 1 year of life

Summary Background Infant adiposity better predicts childhood obesity/metabolic risk than weight, but technical challenges fuel controversy over the accuracy of adiposity estimates. Objective We prospectively measured adiposity (%fat) in term newborns ( NB ) at 2 weeks ( n  = 41) and 1 year ( n  = 30). Methods %fat was measured by dual X ‐ray absorptiometry ( DXA ), PEAPOD and skin‐folds ( SF ). DXAs were analyzed using H ologic A pex software 3.2( DXA v1) and a new version 5.5.2( DXA v2). Results NB %fat by DXA v2 was 55% higher than DXA v1 (14.2% vs. 9.1%), 45% higher than SF (9.8%), and 36% higher than PEAPOD (10.4%). Among NB , P earson correlations were 0.73–0.89, but agreement (intra‐class correlations) poor between DXA v2 and DXA v1 (0.527), SF (0.354) and PEAPOD (0.618). At 1 year, %fat by DXA v2 was 51% higher than DXA v1 (33.6% vs. 22.4%), and twice as high compared with SF (14.6%). Agreement was poor between DXA v2 and DXA v1 (0.204), and SF (0.038). The absolute increase in %fat from 2 weeks to 1 year was 19.7% ( DXA v2), 13.6% ( DXA v1) and only 4.8% by SF . Conclusion Analysis of the same DXA scans using new software yielded considerably higher adiposity estimates at birth and 1 year compared with the previous version. Using different modalities to assess body composition longitudinally is problematic. Standardization is gravely needed to determine how early life exposures affect childhood obesity/metabolic risk.