Experts have urged ministers to delay the introduction of new maths A-levels by a year, amid concerns that the first pupils to take the courses would have sat an old, "very different" GCSE in the subject.
Ofqual, the exams regulator, and the A-level Content Advisory Board (ALCAB) are among those advising the Department for Education to put back the new maths courses to autumn 2017.
Reformed maths A-levels are currently slated for first teaching in schools in September 2016, just a year after the introduction of new, tougher, GCSE maths.
This means that the first batch of teenagers to take the new A-level will have taken a GCSE exam which is significantly different from its successor.
Speaking at a Westminster Education Forum in London today, ALCAB executive director Isabel Nisbet, said: "ALCAB has concluded that the new AS/A-level mathematics content is suitable for the new qualifications, if the first teaching is no earlier than 2017. This is primarily because of the alignment with the new GCSE.
"New GCSE maths is very different from its predecessor and we felt the first cohort doing the new maths must have progressed from the new GCSE not the old. But we don't yet know what the minister's decision is on that."
Ofqual chief Glenys Stacey told the conference that the regulator had also made its position clear to government, adding that it expects ministers to make a decision shortly.
The regulator later confirmed that it is recommending putting A-level maths back by a year, to first teaching in 2017.
Paul Dodd, director of education and learning (reform), at the OCR exam board suggested that the delay would also give more time to look at the content of the maths A-level.
He told the forum: "One of the issues which we've been fighting with is quite simply the pace of reform. The pace of reform is frightening. We do need to slow down and take stock.
"The proposal to delay A-level maths and further maths for a further year is a very sensible one because there is still uncertainty around the issues, around the content, and around problem-solving.
"We hope the minister will take the decision to delay that until 2017, ALCAB, Ofqual and all stakeholder groups have urged him to take that decision."
Speaking after the forum, Brian Lightman, general secretary of the Association of School and College Leaders, said that his organisation would support the delay, adding that it is important that any qualification reform is implemented in the best interests of students.
"To rush them through before the new GCSE is in place makes it very difficult," he said.
Mr Lightman added: "The leap to the new GCSE is enormously challenging, it's going to be a very demanding exam, schools are doing everything they can to prepare pupils for it. To progress beyond that to new A-levels is even more demanding."
The introduction of new maths A-levels is part of a major shake-up of the qualifications, which will see new courses in many different subjects introduced over the next two years.
A DfE spokesman said: "We have noted the advice from Alcab and ministers are considering it. We will make a decision in due course."