By Nick Triggle
Health reporter, BBC News
Over the last few years abortion has been hitting the headlines with many arguing the upper limit should be reduced.
But doctors who are at the front-line of the debate are struggling to come down on either side.
The images of the "walking" feotus were published two years ago
Two years ago images showing a 12-week-old foetus sucking their thumb and appearing to "walk" were published.
Ever since, a debate about the upper limit of abortion has raged.
During last year's general election it hit the headlines when the then Tory leader Michael Howard said he would back moves to reduce the 24-week limit.
This year Cardinal Cormac Murphy O'Connor has met Health Secretary Patricia Hewitt urging her to reduce the upper limit.
And MPs have got in on the act too with 130 MPs - including science and technology committee chairman Phil Willis - have backed a motion calling for a review of the law.
The government has, to date, remained steadfast on the issue saying it is not on the agenda.
The health secretary has even come out to say she is not in favour of lowering the limit despite France, Germany and Italy all setting an upper limit between 12 and 13 weeks.
The 24-week limit was set in 1990 as an amendment to the 1967 Abortion Act.
While the 3D moving images may have been the catalyst which ignited the debate, leading doctors do not believe they provide the intellectual evidence behind the need for one.
Instead, they say the key has been the advances in medical technology which mean doctors are able to keep babies alive even when they are born before 24 weeks gestation.
However, despite the progress over the last decade, doctors still have mixed views over the right way forward.
The abortion limit was debated at the British Medical Association's annual conference last year for the first time since 1989, but despite many arguing for the limit to be lowered, delegates voted against such a move.
Leading doctors, speaking at a briefing organised by the Science Media Centre in London, all said it would be wrong to assume the images proved that foetuses at such a young age were conscious and sentient beings.
ABORTION TIME LIMITS
France: 12 weeks
Germany: 12 weeks
Italy: 13 weeks
Sweden: 18 weeks
US: limits after 26 weeks
Australia: No limit
Dr Donald Peebles, a consultant in foetal medicine at University College London, said the "fantastic" images provided a view of what goes on in the womb that was "completely comprehensible" to the public.
But in scientific terms, they contributed nothing new to the debate over whether the legal time limit for abortion should be lowered from 24 weeks.
He said: "The temptation is to associate foetal movements with adult movements - it's sucking its thumb because it's happy, it's walking because it's going somewhere. I think it's that step that's incredibly dangerous."
Dr Peebles agreed it was now the right time to debate the issue, adding he would not oppose a small reduction in the 24-week limit.
But to illustrate how fraught with difficulties the debate is he added: "My over-riding concern is that the desire to change it will lead to an oversimplification."
Dr Huseyin Mehmet, a researcher in development neurobiology at Imperial College London, said he felt the 24-week limit was about right, although it was just his personal view and others should debate the issue.
"Yes, I work in this field, but that does not make me any more qualified to judge what should be done.
"While I believe the 24-week limit may be right, I may well end up changing my mind if we do have a debate."
Professor John Wyatt, of the London's University College Hospital's department of paediatrics and child health, said one of the issues was that the debate was extremely "polarised" with some seeing it as a black or white issue.
He, too, said he would not oppose a reduction to 22 weeks, adding: "I personally believe these are issues for the whole of society to discuss.
"But I think it is important to discuss quality of life issues within that debate. Some children (born around the 24-week mark) can develop extraordinarily well, but up to 50% will have long-term behavioural, psychological and educational problems.
"The other thing worth considering is that there are very very few social abortions after 19 weeks, it just does not happen.
"And we have to remember, the 24-week limit is not absolute. When the foetus has abnormalities there is no limit on the time of abortion."