The Daycare Trust and the NUS are among organisations that have signed the letter.
The Department for Education is considering reducing the age of the Care to Learn programme to 18 or under to offset the increased costs it expects when the school leaving age rises to 17 in 2013.
Currently, parents aged under 20 are able to apply for up to £160 a week (or £175 in London) to help pay for childcare while they are in education or training.
Under the new plan, parents over 19 would instead have to apply for discretionary funding to help with childcare costs, which charities say would make it harder for young parents to continue in education or take up training.
With Discretionary Learner Support parents do not find out of they will receive the funding until they are just about to start the course.
This means that they can typically have to pay up front for four weeks of childcare in order to keep a childcare place before they know whether their childcare costs will be covered.
In the letter, the charities point out that Care to Learn has made a ‘clear impact on a typically hard-to-reach group of young people’.
They say that before starting learning in the academic year 2008/09, 69 per cent of young parentsreceiving Care to Learn were not in education, employment of training (NEET).
However, only 27 per cent were NEET by early 2010.
They also say that changes would hit women hardest, as 99 per cent of Care to Learn recipients are young mothers.
‘Women have already taken a disproportionate share of wider funding cuts and this must not continue,’ the letter says.
Anand Shukla, chief executive of the Daycare Trust, said, ‘Care to Learn has been incredibly successful in enabling young parents to access employment, education and training opportunities.
‘Changing the basis of such an effective programme runs the very strong risk of encouraging greater reliance on state support.
It is already very difficult to encourage young parents back into education, and this change is likely to make things worse.
‘To be successful as an incentive, finding and paying for childcare has to be made as simple as possible, which is not the case with discretionary funding.
‘Daycare Trust strongly recommends keeping Care to Learn intact, and increasing funding along with demand rather than spreading it more thinly.’
Toni Pearce, vice president of the NUS, added, ‘Care to Learn is vital in supporting the life chances of young parents, particularly young mothers. It is economic folly to cut it and we urge the Secretary of State to intervene and abandon the proposals.’
Other signatories include Platform 51, the Fawcett Society and student organisations.
Penny Newman, chief executive of women’s charity Platform 51, added, ‘Platform 51 sees on a daily basis the impact Care to Learn has on young mothers’ ability to re-engage with education and training.
This relatively small amount of money delivers substantial results for some of the most disadvantaged young people in our society. These proposals risk trapping young mothers in a cycle of disadvantage limiting not only their own future prospects but those of their children and generations to come.’
In the academic year 2009-10, the programme cost around £37 million and provided childcare support to 7,933 young parents. The scheme currently supports around 6,300 young parents.
Sian Nisbett, who runs Dizzy Ducks Day Nurseries, a group of four nurseries in Essex, told Nursery World, ‘Why make it harder for these young parents than it already is? Engaging them in college courses and helping out with their childcare costs not only reduces the chances that they will end up on benefits and unemployed, but in turn increases their child’s life chances and economic outcomes too.
'We have lots of Care to Learn placements at nursery and the proposals would destroy these young parents’ life chances.’