Women suffer a "devastating" impact on their pay after having children, a new study has found.

Research for campaign group the Fawcett Society showed that childbirth marked the start of a "great divide" on earnings, which continued even after children left home.

Before becoming parents, men and women were equally likely to be employed but, after having children, 57% of mothers of under fives were in paid work, compared with 90% of fathers.

Mothers working full-time suffered a pay "penalty", while pregnant women were vulnerable to discrimination, according to the report.

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."