Obesity begins in the womb

August 24, 2006

The number of overweight and obese infants and children under 6 years old has increased dramatically in the United States during the past 20 years. (File photo/Harvard University)

The obesity epidemic in the United States has spread to include children under 6 years old and particularly infants, according to a Harvard study. The study of 120,680 kids is the largest to date to report on such young children. During the 22-year period covered, medical records reveal that the prevalence of overweight children less than 6 years old jumped 59 percent, from 6.3 to 10 percent.

The results show surprising increases in the number of overweight children up to 6 months old. From 1980 to 2001, the increase in overweight infants ballooned 74 percent.

"The obesity epidemic has spared no age group," says Matthew Gillman, an associate professor at Harvard Medical School. "These results show that efforts to prevent obesity must start even before birth."

Increases in overweight children were greater among girls than boys, and larger among Hispanic children than among blacks and whites. The kids were healthy, middle-class children.

Gillman and his colleagues at the Harvard Medical School, Harvard School of Public Health, and Harvard Pilgrim Health Care collected their information from the medical records of 120,680 children who made 366,199 visits to 14 offices of Harvard Vanguard Medical Associates, an HMO in eastern Massachusetts. Gillman believes the findings apply to other areas of the country because national studies have found similar trends among 2- to 6-year-olds. In both the Massachusetts and a national survey, the number of overweight 2- to 6-year-olds rose about 25 percent from 1992 to 2001.

"This information is important to public health because previous studies show that accelerated weight gain in the first few months after birth is associated with obesity later in life," notes Gillman. And obesity has been persistently linked to increases in the risk of heart disease, diabetes, and cancer.

Indexes of weight

Physicians and researchers judge whether someone is overweight or obese by a measure of weight in proportion to height known as body mass index (BMI). People with a BMI of 25 or greater are considered overweight. Those with a BMI of 30 or more are labeled obese. To calculate the BMI of anyone over 2 years of age, divide his or her weight in pounds by height in inches times height in inches (height squared), then multiple the result by 703.

The Harvard study used a different method, known as weight-for-body length, in their analysis. The team then confirmed their results for children older than two years with the BMI charts.

Summarizing the results from the study, published in the July issue of Obesity, Gillman notes that, "our results show that efforts to prevent obesity must start at the earliest stages of development, even before birth. These efforts should include avoiding smoking and excessive weight gain during pregnancy, preventing gestational diabetes, and promoting breast feeding."

"The current obesity epidemic warrants an active role by the medical community both in improving treatment methods and in providing prevention efforts for childhood obesity," notes Juhee Kim, first author of the report. "An active monitoring system of weight status for patients represents an important step toward the evaluation of obesity prevention efforts that have not spared even the youngest children in the United States."

Source: Harvard University