The coronavirus pandemic is threatening to derail women’s careers and take UK society back to a 1950s style of living, experts have warned, as research showed the proportion of mothers responsible for 90 to 100% of childcare increased from 27% to 45% during lockdown.

Researchers at the University of Sussex found 72% of mothers described themselves as the “default” parent for all or most of the time during lockdown, while 67% of women with work commitments also described themselves as such. In addition, 70% of women reported being completely or mostly responsible for home schooling.

Alison Lacey, a doctoral researcher at the university’s school of psychology, said pre-existing inequalities had worsened since the start of the coronavirus crisis.

“Society has regressed to a 1950s way of living, which will have serious consequences,” she said. “We hear about women waking at 5am, working until 9am, then taking on childcare and home learning and doing more work in the evening.”

The impact of school closures means the government has left families to absorb six months of unpaid labour into their households, Lacey said. “This has not been properly acknowledged and policymakers must consider this. The gender pay gap we have been working so hard to close is widening even further.”

More than 2,000 participants with at least one child enrolled in primary school completed a baseline questionnaire and subsequent follow-up surveys as part of the study into family adjustment during lockdown.

Lacey said: “We recognise many dads have stepped up and undertaken more childcare over this period but … women are still overwhelmingly taking on role of primary carer and primary educator.”

Maternal employment was found to be disproportionately vulnerable to the impact of Covid-19, with 73% of mothers saying working from home was “difficult” or “very difficult”. Analysis based on female respondents with a male partner also found women were dominant in seven out of eight categories of domestic labour.

Academics say the findings do not reflect a “battle of the sexes” but rather a situation thrust upon families because of the pandemic. Because men tend to earn more, their jobs have more often taken priority with women more likely to be left providing the childcare, said Lacey.

“Furlough hasn’t been an option for everyone. Many women have been left high and dry. Some have muddled through a full-time job while juggling childcare. Those who have been furloughed fear they will be first in the firing line when it comes to redundancies. Meanwhile women are participating less so they are less likely to be promoted.”

Dr Mary-Ann Stephenson, the director of the Women’s Budget Group, said with widespread redundancies expected when the furlough scheme ends, the government must recognise, reduce and redistribute women’s unpaid work.

“We need policies to protect women against higher levels of redundancies, so companies should be required to report their redundancy rates by sex, and provide additional protection for women who are not able to work because of caring responsibilities,” she said

Stephenson said practical policies that provided childcare support as lockdown eases would be vital to reduce the burden on women amid concerns large numbers of nurseries would close because of financial pressures.

“Then there is redistribution which means men doing more,” she continued. “There is an underlying assumption care is women’s work even when they are the primary earner. To tackle that we need to examine what happens when children are born. If we had properly paid paternity leave for men with a ‘use it or lose it’ clause, perhaps later down the line women would be less likely to be the default parent.”