Almost a quarter of new mothers are feeding their babies cakes and biscuits before they reach six months, when they should only be fed breast milk, researchers have said.
Australian scientists found that some young children were given fatty, sugary and salty foods just a month after being born, even though international guidelines say newborns should have nothing but milk for their first six months.
It is thought that giving them solid foods early could have long-term effects and even make them more likely to suffer obesity when they get older.
Scientists from the Department of Nutrition and Dietetics at Flinders University, in Adelaide, spent a year talking to 587 new mothers on the phone.
Their findings, reported in the journal Nutrition & Dietetics, showed that these babies had a greater chance of eating high fat, sugar and salt foods in their first year of life.
Lead researcher Dr Jane Scott said: "Almost one in four mothers had introduced fruit juice, biscuits and cakes to their infants by six months of age.
"This is a worry because eating habits developed early in life usually continue throughout a person's lifetime - and an overweight child is much more likely to become an overweight adult."