Objective: To determine the period of childhood in which weight relative to height increases in Pima Indian children and young adults in comparison with the general US population.
Methods: Heights and weights of children in the Pima Indian population were derived from either clinical examinations conducted by the Department of Public Health Nursing (from 1-48 months of age), or from examinations in the National Institutes of Health longitudinal survey of health in the Pima population (for birth and ages 5-20 years), and compared with standards for the US population recently published by the National Center for Health Statistics.
Results: Weight relative to height (weight-for-length in children aged <24 months, body mass index at ages > or =2 years) was significantly higher in Pima children at all ages examined after the first month of life. Compared with reference values, the most dramatic increases in weight relative to height occurred in 2 stages of childhood: mean z scores of weight-for-length increased between 1 month (mean +/- SEM: males: -0.2 +/- 0.19; females: -0.02 +/- 0.14) and 6 months (males: 0.8 +/- 0.04; females: 0.7 +/- 0.04) of age; mean z scores for body mass index increased gradually between 2 years (males: 0.4 +/- 0.06; females: 0.4 +/- 0.08) and 11 years (males: 1.4 +/- 0.08; females: 1.4 +/- 0.08) and remained stable thereafter.
Conclusion: Excessive weight gain occurs early in the Pima population with changes relative to reference values most marked in the first 6 months of life and between 2 and 11 years. Interventions toward primary prevention of obesity may need to be targeted at children rather than adults in this population.