Children who start to rapidly gain weight at a younger age are more likely to have higher blood pressure and other signs of future heart troubles as soon as they become preteens, according to new research, reported by Reuters.

Previous studies have suggested children who put on weight in early childhood are more likely to be obese later in life. The new research adds to those concerns.

"There's a natural tendency early in life for children to thin out as they grow taller and gain stature faster than they gain weight," Dr. Mark D. DeBoer, who studies childhood  obesity at the University of Virginia in Charlottesville, told Reuters.

However, "kids hit a point when they start gaining weight at a faster pace," and their body mass index (BMI) - a measure of body fat based on height and weight  -begins to rise. That point is called the adiposity rebound and it typically happens when they are around age four to six, according to DeBoer, who was not involved in the study.

Researchers at Dokkyo Medical University in Mibu, Tochigi, Japan followed 271 children born in 1995 and 1996. They measured the kids' weight and height at least once every year from infant health checks and physical exams at school until they were 12 years old.

Based on each child's growth pattern, researchers determined when children hit their lowest BMI, the age at adiposity rebound. After that, they got bigger every year.

They found that the earlier both boys and girls reached that turning point, the heavier they were at age 12, Reuters reported.

Researchers saw that boys who started getting bigger at age three had an average BMI of 21 as preteens, which is the equivalent of a five-foot-tall boy weighing 108 pounds. They observed that boys who didn't start getting bigger until at least age seven had an average BMI of 17 - the equivalent of the same boy weighing 87 pounds.

Based on their study, boys who reached this turning point at a younger age had higher triglycerides and blood pressure at age 12. Researchers warned that although their numbers were still in the normal range, they could hint at signs of future heart problems.

The link between age at adiposity rebound and heart risks was smaller but also visible in girls, researchers wrote.

"There's a strong possibility that these are children who inherited a genetic predisposition that made them more likely both to have early adiposity rebound and to have metabolic syndrome earlier in life," DeBoer said. Metabolic syndrome is a group of symptoms, including high blood pressure and obesity that are linked to heart disease.

Dr. Stephen Daniels, chair of the Pediatrics Department at the University of Colorado School Of Medicine, told Reuters it is difficult for parents and pediatricians to tell exactly when children are at their adiposity rebound. And it's not clear how to prevent it from happening early.

"The message is probably still more general, in terms of families working with pediatricians and family physicians to make sure that families have a healthy diet and that they have healthy opportunities for activity," Daniels said.