Blood pressure in children and adolescents has risen significantly over the last decade, researchers have found.
Being overweight is linked to higher blood pressure
The US study, in the Journal of the American Medical Association, said much of the increase was due to more children being obese and overweight.
High blood pressure increases the risk of heart disease and stroke.
British experts said it was likely the UK would see a similar rise in child blood pressure levels.
A third of adults in the US are currently estimated to be obese and it is
feared if current trends continue a third of Britons will also be obese by
The researchers from Tulane University, in New Orleans studied 5,582 children aged eight to 17 who took part in health surveys in 1988 to 1994 and 1999 to 2000.
They measured both systolic pressure, which shows the force blood exerts on the artery walls when the heart beats, and diastolic pressure, which shows the force on the arteries between heartbeats.
In 1988 to 1994 the children's average systolic blood pressure was 104.6mm Hg (millimetres of mercury). This rose to 106 mm Hg in 1999 to 2000.
Over the same period, the diastolic pressure increased from an average of
58.4mm Hg to 61.7mm Hg.
In the first survey, 11.7% of the children were overweight, rising to 16.3% 10
'Huge effort needed'
Dr Jeffrey Cutler, who led the research, said past research had suggested that for each one to two millimetre mercury rise in systolic blood pressure, children faced a 10% increased risk of developing hypertension as a young adult.
He added: "The increases found by the study in children's average blood
pressures may seem small, but they can have serious consequences."
Paul Muntner, who also worked on the study, added: "The increase in body mass index (BMI) during this same period accounted for some of the increase in blood pressure.
"Given the relationship between BMI and blood pressure and the high and
unabated increase in the prevalence in overweight in the US, the incidence of
hypertension is likely to increase."
Belinda Linden, head of medical information at the British Heart Foundation (BHF) told BBC News Online: "Due to increasing rates of obesity among children in the UK, it is likely that we will see similar rises in blood pressure at an early age as in the US.
"The main lifestyle factors that influence high blood pressure include inactivity, obesity (leading to insulin resistance) and increased salt in the diet."
She added: "Huge efforts are needed to reverse these worrying trends. Parents, schools, government, health services, industry and the voluntary sector must all work together to prevent children from becoming obese."