The Big Question: With advances in modern medicine, is it it time to re-think the abortion law?

Why are we asking this now?

With Saturday marking the 40th anniversary of the introduction of the 1967 Abortion Act, the debate about abortion rolls on. The Act's main author, the former liberal leader David Steel, says that abortion has now become a form of contraceptive, which was never the intention of his legislation, and the Parliamentary science and technology committee is now looking at the merits of lowering the upper limit on abortions from 24 to 22 or 20 weeks.

Yesterday, health minister Dawn Primarolo told the committee that there was insufficient scientific evidence to suggest that the 24-week limit should be lowered, even though some babies can now survive after even shorter gestation periods.

Critics of the bill always complained that it would open the way to abortion on demand, and the figures show a huge increase over the 40 years that the procedure has been legal: up from 40,000 in 1969 to 200,000 in 2006.

What did Ms Primarolo say?

Dawn Primarolo told the Commons science and technology committee that after being briefed by experts, there would be "no proposals from the Government" to alter the current rules on abortion. She added that the law functions "as intended and doesn't require further amendment at the present time".

"The medical consensus still indicates that whilst improvements have been made in care at the moment that concept of 'viability' cannot constantly be pushed back," she told the committee.

How many abortions are there each year?

In 2006, 201,173 abortions were carried out in England and Wales. That is a near four-fold increase on the number that took place in 1969, the first year in which the effects of the new abortion law were really felt. The vast majority of abortions, some 89 per cent, occurred less than 13 weeks into the gestation period. Around 3,000 of abortions last year occurred 20 weeks or more into the gestation period. It is those that are now concerning anti-abortion groups.

England has also become a sought-after location for women from overseas to have an abortion. Last year, around 7,400 women who were non-residents had an abortion in England or Wales, though this was down from 2005's figure of 7,900.

What's changed since 1967?

Medical science has come a long way since the Abortion Act came into effect. It initially set a 28-week upper time limit on abortions, because at the time there was no chance of a foetus surviving when born that prematurely. As treatments for premature births improved, more babies could survive after such a period, and in 1990, the Human Fertilisation and Embryology Act lowered the upper time limit to 24 weeks.

According to the British Medical Association (BMA), the number of viable births at 24 weeks or less remains "extremely small", and according to Government figures, survival is not possible before 21 weeks. The "viability" of babies born sooner than 22 weeks was 1 per cent, while this figure increases to 11 per cent at 23 weeks.

A forthcoming study into all very premature babies born in England last year is set to produce results very similar to those that emerged after a 1995 study. In other words, there has been little change in survival rates for very premature births over the last decade.

Who is calling for a change in the law?

Leading figures from the church for a start. The Archbishop of Canterbury, Rowan Williams, recently said that there had been "an obvious weakening of the feeling that abortion is a last resort". He added that with around 200,000 abortions now taking place a year, "we may well ask what has happened". He is not alone in his criticism. An open letter signed by Catholic cardinals including Cormac Murphy-O'Connor repeated the idea that the Abortion Act was not now being used simply to tackle illegal abortions. It urged that the "conveyor belt" that could take a woman through to having an abortion should be dismantled.

Anti-abortion groups such as the Pro-Life Alliance (PLA) are campaigning for a 20-week upper limit on abortion, though it is likely that any change to a lower limit would not be so dramatic. The PLA maintains an "absolute opposition" to abortion. There is also concern about home abortions, after the development of drugs allowing abortions to be self-induced.

What's the state of medical opinion?

Major medical associations, such as the BMA and the Royal College of Nursing, are against any lowering of the upper time limit. They base their decision on the question of the "viability" of the foetus. The problem for the medical community is that this term is difficult to define. Viability could mean being born alive, or it could mean having a good chance of survival through childhood.

The British Association of Perinatal Medicine, which represents specialists working with newborn children, has said that the evidence for lowering the upper limit is not strong enough, and has warned against any change to the current law.

Are politicians taking note?

Governments have in the past been strongly influenced by the views of the medical profession. The last occasion the time limit for abortion was lowered, in 1990 under John Major's Government, it justified the decision as being in line with the views of modern medical practice. On that occasion the time limit was lowered from 28 weeks to 24 weeks. That set a clear precedent for the issue to be constantly monitored.

The question of abortion is regarded as a "conscience issue" by parliament, which means that parties do not tell their MPs how to vote over it. They leave it up to each individual politician to decide on his or her own opinion on abortion before voting.

What does the future hold?

The debate shows no sign of subsiding, and the Government's move to lower the upper limit for abortion in 1990 confirmed that it was an issue that had to be constantly investigated by lawmakers. There will continue to be medical breakthroughs in the treatment of very premature babies, and with each breakthrough the pressure to lower the 24-week upper limit will increase.

But while the issue of abortion remains one of personal conscience for politicians, leaders have shown a reluctance to act against medical opinion.

Do we need to rethink our laws on abortion?

Yes...

* Babies who have had less than a 24-week gestation period, the current upper limit for abortion, have been known to survive

* David Steel, who was the architect of the Abortion Act, says that people are now using abortions as a form of contraceptive

* More than 200,000 abortions took place in England and Wales in 2006, up 4 per cent on the 2005 figure

No...

* There has been little change in the 24-week survival rates compared with 1995 figures

* The UK's major medical bodies are advising against any lowering of the upper limit

* The vast majority of abortions occur before 13 weeks of a pregnancy. Only 2 per cent occur after more than 19 weeks