See text below.
Babies left with their grandparents when their mothers return to full-time work become slower learners at school than those who receive paid childcare, says a government-funded study.
The findings will reopen the debate about the effect of working mothers on their children's development and raise questions about the availability of affordable childcare.
The past 20 years have seen a huge increase in employment among mothers of young children. The proportion working part or full time within a year of childbirth has risen from 24 per cent to 67 per cent.
Researchers at Bristol University followed 12,000 children born in the Avon area in the 1990s, examining their development and their mothers' working patterns.
They looked at how well the children performed between the ages of four and eight, assessing them in terms of literacy and numeracy.
Unexpectedly, the researchers found that the type of childcare used by the mother was crucial in determining whether the youngster benefited or was harmed by her absence.
"Those children whose care consisted solely of unpaid care by a friend, relative or neighbour experienced significant detrimental effects," said Liz Washbrook, the report's co-author.
Attendance at a nursery actually led to better outcomes for the children who went to them compared with those raised at home by a non-working mother.
Explaining the findings, Miss Washbrook said: "It would appear that children left with a friend or relative do not find that environment as stimulating.
"Perhaps the relative is not that keen on having to raise the child full time, and they are not trained as child care providers would be." It could be possible that the grandparent was caught in a "caring squeeze"
"There may just be a lack of interest. Yet care by a relative in combination with paid childcare appears to be fine."
A previous study by the social policy research charity, the Joseph Rowntree Foundation, found that where a mother of pre-school children worked full time for longer than 18 months, there was a fall of 12 per cent in the likelihood of that child going on to gain A-levels.
The latest report stated that relatively few mothers in the study made use of paid care before their child reached the age of two, probably due to the prohibitive cost. "The recent increases in financial support for childcare may lead to a shift towards paid care by working mothers," it said.
The report, entitled Working Mums: What Impact on Children's Early Years Development?, by Paul Gregg and Liz Washbrook, was funded by the Department for Education and Skills.
-Reprinted from The Telegraph.