Working mothers with two children receive an average of a fifth less pay than men, according to new research by the women's rights campaigners the Fawcett Society.

Its report, entitled ‘Not having it all: How motherhood reduces women’s pay and employment prospects’ is a new survey of existing research, drawing together the most recent data from academic and government sources.

It found that even mothers working full time experience a pay penalty. Partnered women without dependent children earn 9% less than men on average, but for mothers working full-time with two children the pay gap is 21.6%.

Dr Katherine Rake, director of the Fawcett Society said: “The choice of whether and when to return to employment is of course a very personal one. However, it is critical that those mothers who choose or need to be in paid work should be able to do so without suffering a pay penalty."

The Fawcett Society called for new policy responses to reduce the impact of motherhood on a woman’s earnings. Four priority areas emerge from the report:

- Provide mothers with the support they need to return to jobs at their previous skills levels

- Enforce and extend the law to protect pregnant women and women on maternity leave

- Create substantially more part-time work in higher paid occupations

- Tackle the low pay that exists in sectors primarily employing women