Children in the upper half of the normal weight range are at an increased risk for becoming overweight, obese, and hypertensive later on in life, according to a study published this month by researchers at Harvard Medical School (HMS), Harvard Pilgrim Health Care Department of Ambulatory Care, and Prevention and Children’s Hospital Boston.

The study, published in this month’s Obesity Research journal, monitored 314 predominately Caucasian children from East Boston between two visits.

Beginning in 1978, the researchers measured the weight of the children—then aged between eight and fifteen—and then followed up with them eight to twelve years later.

The male participants and almost a quarter of the female participants became overweight or obese.

The authors of the study were particularly interested in monitoring children with a body mass index (BMI) between the 50th and 84th percentile, who, by physicians’ and researchers’ standards, are classified as being in the high end of the normal weight range.

According to the study, girls and boys with BMIs between the 50th and 74th percentiles were five times more likely than their thinner peers—children who had a BMI that fell below the 50th percentile—to become overweight later in life.

And boys and girls with even higher BMIs—between the 75th and 84th percentiles—were up to 20 times more likely than those below the 50th percentile to become overweight at the time of their follow-up appointments.

Alison Field, lead author of the study and an assistant professor of pediatrics at HMS and Children’s Hospital Boston, said the study shows that children need instruction earlier on in life about how to stem tendencies towards weight gain, and that more children than previously presumed are at risk for such weight gain.

“Our results suggest that children above the 50th percentile of BMI for age and gender might benefit from prevention efforts,” she said.

Matthew W. Gillman, associate professor of ambulatory care and prevention at HMS and another author of the study, also suggested that preventative efforts were necessary to “target the entire weight spectrum.”

Gilman specifically cited fewer TV hours and better diets as two such efforts.

In addition researchers found that boys with a higher BMI were four or five more times likely to have hypertension.

Previous research has already demonstrated that children who are overweight or obese are at an increased risk for being overweight and obese as adults.

But this study broadens that claim to a wider audience, according to other researchers in the field.

Alison G. Hoppin, Associate Director for Pediatric Programs at the Massachusetts General Hospital Weight Center, said that this has stronger implications for more children.

“What this story offers is the perspective that the increased risk also applies to the upper half of the normal weight range, and that the risk is more or less on a continuum,” Hoppin said.