UK employers are “living in the dark ages” and have worrying attitudes towards pregnancy and motherhood, new research has revealed.

Almost six in 10 private-sector employers wrongly believe that during the recruitment process a woman should have to disclose whether or not she is pregnant, a survey by the Equality and Human Rights Commission found.

More than a third of the 1,100 senior decision-makers polled said they thought it acceptable to ask women about their plans to have children before deciding whether to give them a job.

Almost half were under the mistaken impression asking whether women have young children was acceptable.

The figures prompted an angry reaction from equality campaigners.

“Every week, we speak to women who have been treated appallingly by their employers,” said Rosalind Bragg, director of Maternity Action, a charity that advises pregnant women and new mothers on their rights.

“Government action to address the disturbingly high rates of maternity discrimination is long overdue,” she added.

More than 40 per cent of employers asked during the research said women should work for an organisation for at least a year before deciding to have children.

The same amount said that women who have had more than one pregnancy while in the same job can be a “burden” to their team.

And a similar proportion claimed to have seen at least one pregnant woman in their workplace “take advantage” of their pregnancy.

Around a third believe women who become pregnant and new mothers in work are “generally less interested in career progression” when compared to other employees in their company.

The statement that pregnancy puts “an unnecessary cost burden” on the workplace was agreed with by 41 per cent of respondents.

The findings reveal that many employers are decades behind the law, the EHRC said. It called on employers to eliminate pregnancy and maternity discrimination in the workplace for good.

Ms Bragg said the situation had deteriorated rapidly in recent years with an 80 per cent jump in the number of women losing their jobs due to unfair and unlawful treatment by their employer.

“It is two years since release of Government research showing the unacceptable scale of the problem,” she said.

The Government committed to review legal protection against unfair redundancy for new mothers 12 months ago, but it has yet to begin.

Ms Bragg said negative attitudes towards new mothers also affected fathers. Few men take parental leave when they see the harsh treatment women receive when they take time off to care for a baby, she said.

“Maternity discrimination is a key factor in the gender pay gap and has a long-term impact on women’s employment prospects,” she said.

EHRC chief executive Rebecca Hilsenrath said: “It is a depressing reality that, when it comes the rights of pregnant woman and new mothers in the workplace, we are still living in the dark ages.

“We should all know very well that it is against the law not to appoint a woman because she is pregnant or might become pregnant.

“Yet we also know women routinely get asked questions about family planning in interviews.”

A spokesperson for the Women’s Equality Party said: “Women are consistently told that it is their choice to earn less money and be less likely to be promoted to a top job than men.

“But today’s research shows that many employers are prejudiced against women from the very beginning of the interview process.”

The party said legislative and cultural change was now needed, including extending employment protections for women who are on maternity leave to also cover pregnant women, and restoring legal aid so that those have suffered discrimination can pursue justice.

“More widely, businesses and the Government need to look at how they can make sure there is true equality in the workplace,” the spokesperson said.

“That requires universal childcare, more flexible working, and a shared parental leave system that would split the joys and responsibilities of parenthood between both parents and ensure companies stopped seeing having children as something that affects only women.”

Chris Milsom, an employment and equality barrister at Cloisters, said that job interviews were particularly “ripe territory” for maternity discrimination.

He said three reforms could make a significant difference to the situation.

“Many of the instances described in this research would amount to harassment under section 26 the Equality Act,” Mr Milsom said.

“Unlike sex or race, however, there is no specific coverage for harassment related to pregnancy or maternity.”

This deserves reconsideration, Mr Milsom said.

Another area of the law that should be revisited is around combined discrimination. Women are more likely to be subjected to double disadvantage based on sex and age, or race.

“Women who are of the age where they might be looking to start a family or at least perceived as such, are more likely to be subjected to this particular form of ill-treatment,” Mr Milsom said.

Most importantly, equality questionnaires for employers detailing information about things such as recruitment processes were scrapped in 2014.

“As a consequence of that, there is an informational dearth for an applicant,” Mr Milsom said.

“They don’t know who else has been successful in applying for jobs or the basis on which recruitment decisions are made.”

Reintroducing the questionnaires would make a “huge difference” to women pursuing legal action against employers who may have been discriminatory, Mr Milsom said.

Publication of the EHRC's latest research coincides with a roundtable event on Monday discussing issues including the gender pay gap and sexual harassment in the workplace.