The Trades Union Congress (TUC) has therefore called on employers to offer furlough to all parents affected by school closures.
Because furlough is available from a minimum of seven days, parents would therefore be able to share childcare over the coming weeks, the union said.
Prime minister Boris Johnson has also hinted that more schools could be shut in the coming weeks.
The TUC said that a series of “chaotic” statements and last-minute approaches from government has left working parents in real difficulties.
It also expressed concern that not all employers are aware that caring responsibilities are an acceptable reason to furlough
“Employers can help their staff get through this crisis and give them a financial lifeline by offering them furlough,” it said.
School closures due to the pandemic have already had a significant impact on working mums.
TUC polling published in September found one in six (16%) mums – mostly those in low-paid jobs – had been given no choice but to reduce their working hours due to school and nursery closures.
The TUC said it is concerned mums and single parents will be disproportionately affected by school closures once again.
Single parents, nine out 10 of whom are women, are less likely to have someone to share the burden of care with.
TUC General Secretary Frances O’Grady said: “With many schools closed, many families will be frantically trying to find a way to balance their work and childcare commitments.
“Without further action, many will have no choice but to cut their hours or take unpaid leave from work. This will lead to further hardship and will hit mums and single parents hardest.
“Employers must do the right thing and furlough mums and dads who can’t work because of childcare responsibilities. And the government should give all parents the right to work flexibly plus ten days’ paid parental leave each year.”