Children, including babies, are more likely to be overweight than they were in the early 1980s, a US study says.
Overweight babies are on the increase
Harvard Medical School scientists studied a total of 120,000 children under six from 1980 to 2001.
Overall, the proportion overweight rose by nearly two thirds to 10%, while for babies under six months the rate increased by three quarters to 5.9%.
UK experts warned parents the trend highlighted by the Obesity journal was also being seen in the UK.
The study, carried out on children in Massachusetts, found that boys were the most likely to be overweight in the early 1980s, with 7.2% falling into that bracket compared to 5.4% of girls.
Two decades later, 10.8% of boys and 9.2% of girls were overweight - defined as 45% above average when height and weight are taken into account.
And the researchers said it was particularly worrying that the number of newborns just beneath the overweight mark had increased by much more than the other age groups.
The reasons for the increase in weight problems for older children have been linked to levels of inactivity and the consumption of foods high in fat, salt and sugar.
For babies, the research suggested it was linked to the eating habits of women while pregnant and the rate of gestational diabetes, which affects women solely during pregnancy.
Lead researcher Matthew Gillman said: "The obesity epidemic has spared no age group, even our youngest children.
"The 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."
And he added: "These results show that efforts to prevent obesity must start at the earliest stages of human development, even before birth.
"These efforts should include avoiding smoking and excessive weight gain during pregnancy, and promoting breast feeding, all of which researchers have shown to be associated with reductions in childhood overweight."
Paul Sacher, of the Institute of Child Health, said similar trends were likely to have happened in the UK.
"It is not surprising younger children are being affected and this should be a message to parents that they must make sure their children stay active and eat healthily.
"Young children do have more of a chance of growing out of their overweight, but being overweight as a child means you are more likely to become obese as an adult."
But Rosie Dodds, of the National Childbirth Trust, urged parents of young babies not to get too worried about weight.
"It is much better to be guided by the appetite of the baby."
She also pointed out that breast-fed babies tended to be leaner at a year old.