The Office for National Statistics has found almost a third of mums are now in full time employment.
Previous figures from 15 years ago found less than a quarter of mums worked full time.
The findings break down to 29 in 1996. The total number of working mums has also risen, now at 5.3 million, from 4.5 million in 1996.
The general secretary of the TUC, Brendan Barber, said the figures were a testament to family-friendly businesses and working conditions, but warned that the closure of Sure Start centres and increased childcare costs could drive women back out of the workplace:
'The rising proportion of mothers in work over the last 15 years is a ringing endorsement of family-friendly working practices such as better parental leave and pay, and the right to request flexible working. The expansion of quality, affordable childcare through Sure Start centres, now under threat due to local government cuts, has also helped parents find work.
'It is deeply worrying that the Government is about to turn the clock back by abandoning plans to extend family-friendly working, cutting childcare tax credits and forcing hundreds of thousands of women out of work through mass public sector job cuts.'
Speaking to the Daily Express, Jenny North, from Relate, said: 'What's interesting from the statistics is that it seems mothers are more likely to work when they have a partner who can help with childcare.
'We would also like to see employers doing more to create family-friendly environments where balancing work and childcare is a priority, not a luxury.'
What do you think about working mums? Do these stats surprise you?
Do you feel you have no choice but to work full time, or do you choose to rather than need to?
More about working mums on Parentdish:
Karren Brady - work-life balance
Hermione Norris - why working mums can't 'have it all'