The paper published in Work, Employment and Society, shows more higher-paid mothers go back to work full-time in the UK, whereas lower-paid mothers are more likely to go back to work part-time.
Lead author Clare Lyonette from the University of Warwick Institute for Employment Research said many women in more senior positions found they could not return to their previous jobs on a part-time basis after maternity leave.
She said: "There is a culture among many employers that part-time work is not a viable option in more senior positions. We found women who were in senior positions who wanted to go back to work part-time had to downgrade jobs and work well below their abilities.
"A lack of quality part-time jobs has obvious implications for women in the longer-term, reducing their career opportunities and lifetime earnings".
The research team also compared the situation for UK mothers with that of mothers in the US. They found the situation was even worse in the US because of the cost of healthcare.
Lyonette said: "Crippling healthcare costs seem to be one of the main reasons in the US for both parents working full-time. Families cannot afford to lose the benefits of a paid-for healthcare package from their employer so they have to go back full-time.
"It is also likely that the current economic crisis will only increase the pressure on women to continue in, or return to, full-time work, especially if men's jobs and healthcare entitlements are seen to be at risk."
In both countries, the team found a lack of quality part-time work or part-time opportunities in more senior level occupations.
