There is a "growing gulf" between working mothers with top jobs and those lower down the scale who struggle to balance work and children.
Britain's highly educated and high wage mothers are far more likely to remain in employment during their child-rearing years with employers increasingly prepared to help them to do so.
Companies want to keep their high-flyers, those that contribute most to the business and those who are the most costly to train and replace. "Employers seem more inclined to introduce family-friendly policies for their higher status female employees such as managers," said Professor Heather Joshi, of the City University, London.
Such women have more family-friendly working arrangements, better fringe benefits and are more highly motivated to stay in employment.
Clearly, these mothers are also able to balance their babies and briefcases because they can afford a high standard of childcare, the professor says.
Any idea that employers might increasingly apply family-friendly benefits to other employees seems to have foundered on the recession.
The less well-paid and poorly qualified working class mothers have considerably greater difficulty in maintaining "career momentum" after the birth of their first child. Low wages and the cost of childcare is a major reason and the fact that employers are less likely to help them stay in employment.
Around two-thirds of women are still not benefiting much from equal opportunities and in many cases are failing to reach their potential, according Professor Joshi's report, "A Widening Gulf among Britain's Mothers".
The study, which is featured in the Economic and Social Research Council's new publication Business Connect: a brief guide to ESRC business research, also shows that women in full-time work find it much easier to keep their jobs after giving birth than part-timers.
Professor Joshi believes that the Government's policy of cutting benefits to lone parents is misguided. She argued that while state help should be restructured, it should offer incentives and help for people to get back to work, rather force them into employment.