Muscularity and Fatness of Infants and Young Children Born Small- or Large-for-Gestational-Age

• Published in: Pediatrics (Evanston) 1998-11, Vol.102 (5), p.e60-e60
• Main Authors: Hediger, Mary L, Overpeck, Mary D, Kuczmarski, Robert J, McGlynn, Andrea, Maurer, Kurt R, Davis, William W
• Format: Article
• Language: English
• Subjects: Adipose Tissue; Anthropometry; Birth Weight; Body Constitution; Child, Preschool; Fetal Macrosomia; Health Surveys; Humans; Infant; Infant, Newborn; Infant, Small for Gestational Age; Muscle, Skeletal; Pediatrics; Regression Analysis; United States
• ISSN: 0031-4005; 1098-4275
• DOI: 10.1542/peds.102.5.e60

There is growing interest in the extent to which body composition, both short- and long-term, differs in infants and children born at the extremes of birth weight. This is because a growing number of studies have linked low birth weight and fetal growth restriction to the chronic diseases in adulthood that often are obesity-related, and there is also evidence to suggest that heavy infants may be at increased risk for obesity in later life, again with the attendant obesity-related chronic diseases. Our objective was to compare anthropometric indices of body composition of infants and young children born small-for-gestational-age (SGA, /=90th percentile) with those of normal birth weight status (appropriate-for-gestational-age, AGA) in a US sample. National sample of US-born non-Hispanic white, non-Hispanic black, and Mexican-American infants and young children, 2 to 47 months of age, examined in the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994), for whom birth certificates were obtained. The primary outcomes were normalized anthropometric indices (z scores or standard deviation units [SDU]) of nutritional status and body composition (mid-upper arm circumference, triceps and subscapular skinfolds, mid-upper arm muscle and mid-upper arm fat areas (UFA), and the arm fat index). The outcomes thus were scaled to permit comparison across chronologic ages. The prevalence of SGA was 8.6%, appropriate-for-gestational-age 80.9%, and LGA 10.5%. From ages 2 to 47 months, for infants and young children born SGA, there was a persistent overall deficit in muscularity (mid-upper arm circumference and mid-upper arm muscle area) of approximately -0.50 SDU, but less of a deficit in fatness, particularly at the youngest ages. For infants and young children born LGA, there was a surfeit in muscularity of approximately 0.45 SDU, with less of a surfeit in fatness, particularly at the youngest ages. Across all ages, the mean UFA showed a statistically significant deficit for SGA children (-0.27 +/- 0.10 SDU) and surfeit for LGA children (0.24 +/- 0.08 SDU). At individual ages for UFA and at individual and all ages combined for skinfold thicknesses, there were no significant differences in level of subcutaneous fatness in the three birth-weight-for-gestational-age groups. There was a tendency in the first year for the arm fat index (% arm fat) to be significantly higher for SGA infants, but the e