Women with children face a wider gender pay gap, says a new report from the Institute for Fiscal Studies.

In the 12 years after a woman returns to work after having a baby, the gender pay gap increases until they are 33% behind their male colleagues, on average.

Part of the reason, says to the report, is that women who choose to cut their hours when they return to work are denied promotions.

This means the hourly wages of male colleagues move further and further ahead of theirs, leaving them paid a third less by the time their first child is 12.

UNISON general secretary Dave Prentis called for a level playing field in career and pay progression, saying”  “It is a national disgrace that four decades after the Equal Pay Act became law women continue to lose out in this way and are effectively being penalised for having children.

“While we welcome the reduction in the pay gap for full-time workers, this masks a huge divide between them and part-time workers.

“In some sectors such as local government, the gap is actually getting bigger. Action must be taken to make employers end this discrimination.”

Institute of Fiscal Studies: The gender wage gap