A fifth of working parents could quit their jobs or reduce their hours because of childcare costs.
A survey of 1,000 parents of children aged up to 16 also found that many were planning to cut back on essentials this year because of the financial strain of childcare.
More than two thirds of those polled by the charity 4Children paid for childcare, and around one in five of those said they are thinking about reducing their working hours or quitting their job.
Anne Longfield, chief executive of 4Children, said: "Childcare represents a huge financial challenge for most parents and our poll shows the real impact costs are having on family life - from giving up work to cutting back on essentials.
"Removing parents' choice as to whether or not they continue to work after having children is not the answer for families or for the economy.
"Parents of the youngest children are feeling the pressures most acutely and are calling on politicians to do more to help, particularly with the cost of childcare.
"The family vote will be key at the ballot box in May and 4Children is throwing down the gauntlet to politicians to set out how they will ensure childcare meets the needs of modern family life."
As usual, politicians don't agree on what the issue is or how to tackle it.
Shadow education secretary Tristram Hunt, told the BBC: "Under David Cameron, childcare costs have rocketed by 30 per cent since 2010. Wages are down by £1,600 and the availability of childcare has plummeted.
"Labour's plan for childcare will make work pay and boost the economy. We will increase free childcare for working parents with three and four-year-olds from 15 to 25 hours, making a real difference to hard-pressed parents.
"Our legal guarantee of a childcare place for parents of primary school children will also help mums and dads balance work and family life."
A Government spokesperson said: "We are doing more than any other government to tackle the cost of childcare, with funding for early education for two, three and four year olds rising by over £1 billion during the course of this Parliament.
"The evidence shows there are more people in work than ever before, in particular more women, and the gender pay gap has fallen to its lowest on record.
"After 12 years of consistently rising childcare prices, costs are stabilising in England and even falling for some types.
"All three-and four-year-olds now receive 15 hours of free childcare a week, and we have extended this to around 40 per cent of two-year-olds from disadvantaged backgrounds.
"The introduction of tax-free childcare will give almost two million families the opportunity to receive up to £2,000 of support per child."