Mums in England face a “substantial and long-lasting reduction” in earnings after having children, according to new findings from the Office for National Statistics (ONS).

Five years after having their first child, mums’ earnings drop by an average of £1,051 a month compared with their salary one year before having a child.

Mums’ earnings continue to be affected after the births of second and third children.

Rachel Grocott, chief executive of campaign group Pregnant Then Screwed, called the findings “completely abhorrent” and said the impact of the motherhood penalty is “not just unfair – it’s avoidable”.

In the first dataset of its kind, the ONS has looked at the earnings and employment status of mums after having a first, second and third child over an eight-year period from April 2014 to December 2022.

Mums earn £313 a month less on average five years after the birth of their second child, and £689 a month less five years after their third child. Each figure is compared to their salary one year before each birth.

Mums suffer “maximum losses” in the first year after their children are born, when they are more likely to take extended parental leave than dads.

When compared with a mum’s earnings in the year before the birth of a child, the total loss in earnings over five years was:

• £65,618 for a first child
• £26,317 for a second child
• £32,456 for a third child

Femilola Miller, from London, has three children aged seven, five and three.

Before starting a family, she and her husband David had similar salaries, but he now earns £55,000 a year more than her.

Both she and her husband took several months off work after the birth of each child, “but every time my husband went back to work, he got a promotion”.

“Mothers are not compensated even if they return to work full time and are dedicated to their career.”

She believes the motherhood penalty is “engrained in society” and some people enforce the stereotypes “without even realising”, she says, remembering several comments people had made to her about whether she would return to work after having children.

“It was not even a question about what was going to happen to David’s career,” she says.

“I had a career before I had children and I want to carry on working full-time.”

Although the gender pay gap is slowly reducing in the UK, women working full time still earn 7% less than men.

Joeli Brearley, founder of Pregnant Then Screwed, said the motherhood penalty was “a perfect storm of bias, outdated legislation and cultural norms”.

She added “the vast majority” of the gender pay gap is linked to the motherhood penalty, which can be attributed to a number of factors, including:

• unaffordable childcare costs for some families
• an unbalanced parental leave system
• some jobs not offering flexible and part-time working hours
• pregnancy and maternity discrimination

The government has introduced 30 hours a week of funded childcare for working parents and is undertaking a review of parental leave.

New laws also came into force in England, Wales and Scotland last year which give women greater protection against redundancy while pregnant or on maternity leave.

But, according to research from Pregnant then Screwed and Women in Data, up to 74,000 new or expectant mums lose their jobs each year due to pregnancy and maternity discrimination.

Evie, 33, from Newcastle, says she feels as though her career is “on hold” until her daughter goes to school.

Evie initially reduced her hours at work when three-year-old Ellie was born, but now works 35 hours a week in the NHS.

She wants to retrain as a therapist, but doing so would mean she could no longer work from home, which isn’t compatible with her childcare arrangements.

She described becoming a mum as “the best thing that’s happened to me, but career-wise, it has been a punishment”.

“You’re expected to be a parent like you don’t work, but work like you haven’t got kids. You can’t win.”

Emma Potts, manager of Market Place Cafe in Stoke-on-Trent, says it is “a really difficult balance” for small businesses like hers to accommodate flexible working, part-time hours or maternity cover.

“We always try to be as supportive as possible, but the reality is that in a small team, flexibility is much harder to manage.”

If staff members were to reduce their hours to part-time, “it would cause real issues”, she says.

“Ultimately, smaller businesses like ours don’t have the luxury of large teams or spare capacity.

“Every shift matters, every deadline matters, and every absence makes a difference.”

Katie Guild, co-founder of Nugget Savings, a business that helps new and expectant parents with financial planning, says the impact of having children can be “shocking” on finances, but there are a number of things parents can do.

This includes checking which benefits you are entitled to and ensuring your employer still contributes to your pension based on your salary as it was before maternity leave.

“Unfortunately, a lot of what we deal with is mothers having difficult situations with their employers and not knowing whether they have a leg to stand on legally,” she says.

“Knowing your rights is really crucial.”