The BBC reports that the Institute for Fiscal Studies has found that after returning to work, women miss out on promotions and accrue less experience than men, so causing their earning power to diminish.

This causes the wage gap between those affected and not to steadily widen over the years, growing to 33% of men’s hourly pay rates over a period of 12 years

This is despite the fact that one of the IFS report’s authors Robert Joyce said the impact was not felt immediately.

He added: "Rather, women who work half-time lose out on subsequent wage progression, meaning that the hourly wages of men (and of women in full-time work) pull further and further ahead.

"In addition, women who take time out of paid work altogether and then return to the labour market miss out on wage growth.”

The 33% figure is also much greater than the average 18% less women are paid than men.