Early-life risk factors such as fast food exposure and a TV in a child's room may explain much of the previously observed racial-ethnic disparities in childhood obesity rates, researchers found.
In a prospective pre-birth cohort study, black and Hispanic children had significantly higher body-mass index, higher total fat mass index, and overweight and obesity prevalence compared with white children, reported Elsie M. Taveras, MD, MPH, of MassGeneral Hospital for Children in Boston, and colleagues.
But, compared with white children, the other groups had significantly higher rates of such risk factors as fast foods and sugar-sweetened drinks in their diets, short sleep duration, and early introduction of solid foods.
"Obesity is disproportionately prevalent among racial/ethnic minority children, and recent trends suggest that these disparities are widening," the authors wrote online in JAMA Pediatrics. "Our findings suggest that modifiable risk factors throughout the life course, including infancy and early childhood, as well as social conditions in childhood and transgenerational obesity, are critical to understanding how disparities in childhood obesity arise."
In the study, Taveras and colleagues tracked 1,116 mothers (63% white, 17% black, 4% Hispanic) and their children from a multi-group practice in eastern Massachusetts who were enrolled from early pregnancy to age 7 in the so-called Project Viva study. The women were questioned at the end of their first and second trimesters, immediately after delivery, and at 6 months, 3 years, and 7 years later. Researchers measured children's physicality and asked about obesity risk factors as well as socioeconomic information.
Early-life risk factors during pregnancy included gestational diabetes and maternal depression in the second trimester, the study stated. Risk factors during infancy included rapid infant weight gain, early introduction (before 4 months) of solid foods, and mixing breast-feeding with formula or solid foods before 6 months.
During early childhood, risk factors included drinking sugar-sweetened beverages such as soda and flavored fruit drinks and milk at 2 years, and eating fast-foods at age 3. Lack of sleep (less than 12 hours per day from 6 months to 2 years) and keeping a television in a child's room at age 4 were additional risk factors.
More than half of the black and Hispanic children had TV sets in their rooms, compared with just 6% of white children. And more than 80% of black and Hispanic children had eaten fast foods by age 3, versus 65% of white children.
Adjusted for socioeconomic factors and parental body-mass index, the differences were attenuated but still significant for black and Hispanic children.
The study was limited by self-report, the authors indicated, and did not measure lifestyle, cultural, or environmental determinants of diet or lack of exercise. Not all childhood risk factors were accounted for and could limit the explanation of racial and ethnic disparities in obesity. Also, the Hispanic sample was small, they stated.
"We know that, already by the age of 2, black and Hispanic children have close to double the rate of obesity of white children in the U.S. "Our finding that most of these racial/ethnic differences can be explained by behavioral risk factors indicates that designing and implementing interventions to reduce those risk factors during pregnancy, infancy and early childhood could help eliminate racial and ethnic disparities in childhood obesity."