Association between weight at birth and body composition in childhood: A Brazilian cohort study

Previous studies have shown that the association between birth weight and obesity later in life apparently follows a U-shaped curve. However, due to the continuous increase of mean birth weight in several countries worldwide, it is expected that higher birth weight will play a more important role as a risk factor for further obesity than low birth weight. This study investigated the association between birth weight and body composition of children in order to establish their relationship in an earlier period of life.

Prospective cohort study carried out from 1997 to 2006 in Jundiai city, Brazil, involving 486 children at birth and from 5 to 8 years of age. The following anthropometric measurements were determined: birth weight, weight, height, waist circumference and triceps skinfold thickness. Fat mass percentage, fat mass and fat-free mass were measured by electrical bioimpedance analysis by the 310 Body Composition Analyzer, Biodynamics(®). Five multiple linear regression models were developed considering waist circumference, triceps skinfold thickness, fat mass percentage, fat mass and fat-free mass as markers of body composition, and outcomes.

Significant positive associations were observed between birth weight and waist circumference (p<0.001), triceps skinfold thickness (p=0.006), fat mass (p=0.007) and fat-free mass (p<0.001). Approximately 10% of the children presented excess body fat assessed by bioimpedance, and 27.6% of them had central adiposity (waist circumference ≥95th percentile).

Intrauterine growth, assessed by weight at birth, was positively associated with body composition of children aged 5-8 years, indicating that those with the highest birth weight are more at risk for obesity, and probably to chronic diseases in adulthood.