While there is an existing knowledge of the gender pay gap between men and women, the IFS has released new research which claims women with children face an even wider gap.
Robert Joyce, Associate Director at the IFS, said: "There is already a significant gender wage gap of about 10% per hour before children come along but it then widens very significantly after that point."
Joyce explains that it's not an instant division and that the gap instead widens gradually, year on year after a woman has her first child.
The gap reached around 33% by the time the first child hits 12-years-old.
But, why is this happening? Women reducing their hours is one factor with the amount they are paid per hour not growing.
He said: "Part time workers don't seem to get the wage progression that full time workers do, so they fall further and further behind their peers."
Adding: "It could be due to people missing out on formal training opportunities which enable them to increase their skills and enable them to earn more.
"It could be something informal like missing out on social interactions and building up networks that help to get promotions.