In the study of more than 2,500 UK mothers, about 40% said they could not find a suitable position in their chosen field when trying to re-enter the workplace, and 10% who found a position said it lacked flexibility.
The study found 19% have had to take a lower level position after a career break.
Gillian Nissim, founder of workingmums.co.uk, said the amount of women seeking retraining after having children shows a "big appetite" for more flexible working to fit around family life.
"These women have years of experience and have been working at senior levels," said Nissim.
"The research showed a lack of flexible jobs is the main barrier to mums getting back to work. The most progressive employers have significantly improved their recruitment and retention figures for women through addressing this issue and some have initiated innovative programmes for women who have taken career breaks."
The study showed that a lack of opportunities for returning mothers has led to many considering setting up their own business.
