Official charts used by doctors and health visitors to check infants are growing correctly date back to 1990, when around half of babies were breastfed and half given formula milk.
Today, three-quarters of babies are breastfed, and as those fed on formula gain weight at a quicker rate, mothers following the charts may have been overfeeding.
Studies suggest overfed babies are at greater risk of becoming obese later in life and suffering associated illnesses such as diabetes.
The weight charts given to British mothers since 1990 are based on studies carried out between 1978 and 1993. The World Health Organisation now plans to release new recommended growth charts by the end of 2007.