According to a recent study toddlers who were left with their grandparents are more likely to have behaviour problems and tended to be more badly behaved.

The study carried out by the University of London of 5,000 toddlers who were left with older family members while the parents were at work found these children more likely to have trouble getting along with other children.

These children were also found by the researchers to be less adept with numbers and letters as compared to children who were in a nursery or creche and were not as prepared to move on to primary school.

Researcher Kirstine Hansen said grandparents are the caretakers for 35 % of parents who opt to return to work once the child is between nine months to three years of age. "At this young age the majority of care is being done by grandparents," she said.

"In the past grandparents have had a bad press but this study shows that in terms of cognitive skills and vocabulary children cared for by grandparents do best.

"However children in formal care are more ready for school. They do better in readiness for school tests than children in any other type of care, including those with childminders or nannies.

"What was surprising was the finding that children who are cared for by grandparents are more likely to have behavioural problems."

The study comes as the number of working mothers in Britain has seen a considerable rise from 51 % to 64 % over the past 30 years and gives rise to concerns about the emotional and behavioural development of the children. These numbers, feel experts could go up some more amid the recession and fewer families being able to afford professional childcare. The study by academics at the Institute of Education, part of the University of London, studied 4,800 children whose mothers had gone back to work when the children were nine months old. They found that 35 % of these children were being cared for by their grandparents, 23 % were attending a nursery or creche and 17 % were being looked after by child minders.

When the children were three years old their mothers were interviewed and the children who were looked after by their grandparents were reported to have a more difficult relationship with other toddlers, the effect being more pronounced in boys.

These children were also found to score less in their grasp of letters, numbers, shapes, sizes and colours. However they had better vocabularies particularly if they were from middle class homes whose mothers were well educated and married.

The report, published in the Journal of Social Policy said, "Nurseries and creches are more likely to offer structure and content to daily activities with children and their staff are more likely to be trained, to have better facilities and resources and to provide more educational stimulation."

Dr Richard House, of Roehampton University's Research Centre for Therapeutic Education, said: "Any view that institutional nursery care can be preferable to the care of a grandparent for very young children, no matter how apparently respectable the research source, must be seriously questioned.

"Research from across the world is increasingly showing that, all things being equal, institutional childcare for children under three can be harmful, with negative impacts on both behaviour and capacity for sociability."

In conclusion Dr Hansen and Dr Denise Hawkes, the authors of the report, said, "Our research shows that grandparent care contributes both positively and negatively to child outcomes, and perhaps with government support this situation could be improved."