WASHINGTON – Childhood obesity is soaring in the United States, especially among Hispanic and African-American children. At the heart of this “epidemic” are dietary and behavioral factors that are linked to stress and poverty rather than race and ethnicity, and the risks may even begin prenatally, according to experts attending an Institute of Medicine forum on early childhood obesity.
Based on data from the 2009-2010 NHANES (National Health and Nutrition Examination Survey), over 8% of children aged 2-5 years in the United States are obese; based on ethnicity, 18% of Hispanic boys and 15% of Hispanic girls in this age group are obese. Nearly 18% of U.S. children aged 6-11 years are obese; nearly 29% of Hispanic boys and 26% of non-Hispanic black girls in this age group are obese.
“If we’re looking for reasons why black and Hispanic children have these disparities ... then we’re looking at what happens in their early years and during pregnancy,” Dr. Elsie Taveras, chief of general academic pediatrics at Massachusetts General Hospital, Boston, said at the IOM meeting.
Dr. Elsie Taveras
Chief among the culprits responsible for the “metabolic programming of risk” is the mother’s pregestational weight, according to Dr. Lisa Bodnar, associate professor of endocrinology at the University of Pittsburgh. “Children may already be programmed to become obese as a result of their intrauterine exposure to an obesogenic environment.”
A 2013 report from the Centers for Disease Control and Prevention found that about 1 in 5 women aged 20 years and older who delivered a live-born infant in 2009 were obese prior to becoming pregnant. The prevalence of obesity was highest among women who were 35 years of age and older (24%); were black, non-Hispanic (32%); had a high school education (28%); and reported Medicaid as their source of insurance coverage before pregnancy (30%). The prevalence of obesity was lowest among women who were 20-34 years of age (22%); were of “other” race/ethnicity (13%); had more than a high school education (20%); and who reported having private insurance coverage before pregnancy (20%), according to the report.
Studies have established that pre-pregnancy body mass index is highly correlated with rates of childhood obesity, but Dr. Bodnar believes the most elegant study, published in Pediatrics in 2004, links the birth records of 8,500 children born to low-income mothers in Ohio with corresponding Women, Infants, and Children data for their children’s respective weights and heights at ages 2, 3, and 4 years. Mothers with pre-pregnancy BMIs in the obese and severely obese ranges had a 3-4 times greater probability that their children had similar BMIs.
More recent U.S. data show that nearly half of all expectant mothers with normal pregravid weights also gain more weight prenatally than the IOM-recommended amounts. The tendency is even more prevalent in those with BMIs in the overweight and obese ranges: 70% of women with pre-gestational BMIs between 25 and 29.9, and 65% of those with BMIs of 30 and over gain too much weight. A 2013 meta-analysis published in JAMA correlated these weight gain patterns with a 90% increased risk of children being obese before the age of 5 years, and a 40% overall lifetime increased risk of obesity.
Stress and sociodemographic factors also can contribute to overeating and unhealthy eating, Dr. Mary Jo Messito, director of the Starting Early Child Obesity Prevention Program at Bellevue Hospital, New York, said in an interview. “High stress can lead to eating higher levels of sugary and processed food.” In lower socioeconomic neighborhoods, processed and fast foods can also be more affordable and more readily available, she added.
At least one study (Sleep Med Rev. 2012 Jun;16[3]:203-11) has established a link between later bedtimes and obesity.
This generation of children sleeps nearly a half hour less per night than did their parents, Dr. Taveras said, and the culprits include later bedtimes, the intake of caffeinated and sugary beverages, and electronic intrusions. A television left on in the room where the child sleeps can make the child dependent upon external means rather than self regulation for putting themselves to sleep, according to Dr. Taveras’ research, published in Pediatrics.
Dr. Taveras also lead a 7-year prospective prebirth cohort study (JAMA Pediatr. 2013 Aug 1;167[8]:731-8) of 1,116 mother and child dyads. In that study, the higher levels of obesity in racial and ethnic minority children were linked to modifiable risk factors. Black and Hispanic 2-year-olds were twice as likely as white ones to have had a cola or other sweetened or caffeinated drink prior to bedtime. By age 4 years, 6.4% of white children, 53% of black children, and 61% of Hispanic children in the study fell to sleep with a television on.