Babies who are still drinking from a bottle after the age of 1 are more likely to become obese, US researchers said Thursday.

A study of almost 7,000 children by scientists at Temple University in Philadelphia found that those who were still being put to bed with a bottle of milk at age two were 30 percent more likely to be obese at age five.

"A 24-month-old girl of average weight and height who is put to bed with an eight-ounce (230-gram) bottle of whole milk would receive approximately 12 percent of her daily caloric needs from that bottle," said Rachel Gooze, from the university's Center for Obesity Research and Education.

The team found that around 22 percent of the children they studied used a bottle as their primary drink container, or were put to bed with a bottle. Of this group, nearly 23 percent were obese by the time they were five-and-a-half years old.

"Children who were still using a bottle at 24 months were approximately 30 percent more likely to be obese at 5.5 years, even after accounting for other factors such as the mother's weight, the child's birth weight, and feeding practices during infancy," said co-author Dr. Robert Whitaker.

They said that drinking milk from a bottle beyond infancy could contribute to later weight gain by encouraging the child to consume too many calories.

Doctors and parents should wean babies off bottles by their first birthday, said the researchers, writing in The Journal of Pediatrics.

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