Mothers do not harm their young children emotionally or socially by going out to work, according to research that offers reassurance to women worried about juggling jobs and family responsibilities.

In fact, girls seem to gain from being in a household where their mother works, according to analysis of families with children born in 2000. In a project funded by the Economic and Social Research Council, a team from the department of epidemiology and public health at University College London found no evidence of detrimental effects on the young children of mothers working part-time or full-time.

The results were published in the Journal of Epidemiology and Community Health on Friday.

The ideal scenario for children of both sexes was for both parents to live at home and for both to be working, a finding that will encourage policymakers' moves to help families stay together, if not critics of the rising numbers of working mothers.

Anne McMunn, who led the research, said there seemed to be many benefits from both parents working "as long as parents are supported, do not have to work long hours and are able to combine child-rearing with paid work ... In this study we did not see any evidence for a longer-term detrimental influence on child behaviour of mothers working during the first year of life."

Thousands of parents, mainly mothers, answered questionnaires about their children in infancy and when they were three and five. They covered external behaviours such as hyperactivity, tantrums and aggression, and internal ones, including unhappiness, tearfulness and worry. There were more than 12,000 responses for each stage, and the percentage of mothers working rose from 55% in children's infancy to 60% at the age of five.

The study, which looked only at white children because of statistical difficulties in sampling other ethnic groups, is the latest contribution to the decades-long, often fraught debate about whether mothers' paid employment is good or bad for their children. Among many conflicting messages, there have been suggestions that young children looked after by people other than their parents may be more prone to bad behaviour, that there could be a link between working mothers and overweight children and that working mothers in steady relationships are the healthiest women.

The new study suggested that boys whose mother was the breadwinner had more difficulties at the age of five than those living with two working parents. Girls whose father was the breadwinner were more likely to have problems than when both parents were earning.

The idea that working mothers might act as behavioural and emotional role models for their daughters needed more investigation, McMunn said. She conceded that researchers were relying on the evidence of parents alone, but said the results of the next checks, made on children's behaviour at the age of seven, would include the views of teachers.

Katherine Rake, chief executive of the Family and Parenting Institute charity, welcomed the research paper. "This study shows what mothers know intuitively. If you are able to get the balance right, your child and your career can both flourish."