Objective: To determine the types of subcutaneous adiposity represented by different measurements of skinfold thickness that are associated with birth weight in white (n=759), Black (n=916) and Hispanic (n=813) American children aged 5-11 y. We also determined the contribution of birth weight to ethnic differences in subcutaneous and central adiposity.
Design and methods: Data for this analysis were from the Third US National Health and Nutrition Examination Survey. The outcome measures were triceps, subscapular, suprailiac and thigh skinfold thicknesses at 5-11 y of age. Central adiposity was defined as ratios of subscapular to triceps (STR) and central-peripheral (CPR) (subscapular+suprailiac)/(triceps+thigh) skinfolds. Partial correlation analyses were used to determine the association between birth weight and measures of subcutaneous fatness, while multiple linear regression analyses were used to determine the independent contribution of birth weight to ethnicity variations in subcutaneous and central adiposity adjusting for sex, age and BMI.
Results: Overall, birth weight was negatively associated with subscapular skinfold and central adiposity in White, Black and Hispanic American children (P < 0.05). Birth weight was also negatively associated with suprailliac skinfold in both Blacks and Hispanics (P < 0.01) and with sum of the four skinfolds in Blacks (P < 0.05). Compared with White, Black ethnicity was negatively associated with triceps, suprailliac thigh and sum of skinfold thicknesses controlling for birth weight, sex, age and BMI (P < 0.01). Compared with White, Hispanic ethnicity was negatively associated with triceps, thigh and sum of skinfold thicknesses (P < 0.01). Both Black and Hispanic ethnicity was positively associated with STR and CPR (P < 0.01).
Conclusions: In this population of American children, the association of birth weights with subcutaneous and central fat accumulation may be due to fetal programming. Since the impact of fetal conditions is likely to be modified by life course, defining the interaction between factors that are present at birth and subsequent exposures is one of the essential challenges for future research.