A survey of more than 2,000 women by Santander found that only a third of those returning to work after starting a family said that the time away had not affected their job progression.
One in four mothers had changed careers after having children, to better suit their family life, and a similar number had switched jobs to one which was less professionally rewarding but was better for their family.
One in 11 (9%) of mothers have taken a career break to focus on their family and 6% say that they have given up work altogether as they could not juggle work and family life.
Simon Lloyd, human resources director at Santander, said: "These findings show that companies need to do more to help women achieve a suitable balance between family and work that allows them to achieve their career aspirations.
"We believe that the loss of talented, experienced women from Britain's companies is one of the biggest challenges that need to be overcome if the UK is to compete in an increasingly competitive global marketplace."
The research among 1,500 working mothers, by Swedish clothing company me&i, also revealed that the main causes of work-related stress included dealing with family emergencies, such as a child's illness, and having to leave the office early to do the school run.
Employment Relations Minister Jo Swinson said: "The current workplace arrangements for maternity leave are old-fashioned and rigid. That is why we plan on introducing measures for shared parental leave between working parents and extending the right to request flexible working to all employees.
"These changes give us a great opportunity to make our workforce even more flexible, help working families and boost economic growth. We want to shatter the myths that it is mainly a woman's role to stay at home and look after the child and that flexible working only has benefits for parents and carers."