Interviews with 1,364 mothers revealed that those who work – especially part-time – were happier than women who stayed home to look after their families.
Researchers analysed more than 10 years of interviews, starting in 1991, soon after the mothers had their kids.
"In all cases with significant differences in maternal well-being, such as conflict between work and family or parenting, the comparison favoured part-time work over full-time or not working," said lead author Cheryl Buehler, from the University of North Carolina, whose findings are published in the American Psychological Association's Journal of Family Psychology.
"However, in many cases the well-being of mums working part time was no different from mums working full time."
For example, mothers employed part time reported better overall health and fewer symptoms of depression than stay-at-home mums.
There were also no reported differences in general health or depressive symptoms between mums who worked part time and those who worked full time.
The study also found that mothers employed part-time were just as involved in their child's school as stay-at-home mums, and more involved than mums who worked full time.
In addition, mothers working part time appeared more sensitive with their pre-school children and they provided more learning opportunities for toddlers than stay-at-home mums and mums working full time.
"Since part-time work seems to contribute to the strength and well-being of families, it would be beneficial to employers if they provide fringe benefits, at least proportionally, to part-time employees as well as offer them career ladders through training and promotion," said Prof Marion Brian, co-author of the study.
Are you a working mum or stay-at-home mum? Have you done both? Did you find being at home full-time depressing or wonderful?