Working women with children are significantly happier than stay-at-home mothers, regardless of how many hours they work, a survey has said.
Mothers are said to be happier when their children go to school
For men, meanwhile, life satisfaction depends on having a full-time job.
The study by the Institute for Social and Economic Research suggests non-working mothers are more satisfied with life once their children start school.
For men, the presence of children brings no increase in life satisfaction.
"Perhaps it is not surprising that fertility in Britain is declining," the report said.
Time and money
The Job Satisfaction and Family Happiness survey also found that job satisfaction for women with partners is greater when they work part-time, irrespective of how small or large these jobs are.
It points out that women overall may be working as many hours as men, when the time spent on household tasks like cooking and childcare is taken into account, but a smaller proportion of their time is spent in paid work.
The report says that more effort should be put into improving the quality of part-time jobs, where women often suffer career disadvantage.
And it argues that lowering the cost of child care would enable more women to work part-time, increasing their overall satisfaction.
Other research has not always taken the same point of view.
Another report, conducted by the Centre for Policy Studies in 2003, said nearly half of working mothers would prefer to stay at home with their children if not for money worries.
And a 2006 government survey found that more mothers said the desire to spend more time with their children was stopping them from working longer hours.
The research was based on questions in the British Household Panel survey, a nationally representative sample of 5000 households (10,0000 individuals) who are surveyed every year. It uses data compiled between 1996 and 2006.