A huge row has erupted over a campaign to decriminalise abortion.

MPs, midwives, various Christian groups and members of the public have waded in to slam the Royal College of Midwives' decision to support a call for the limit on abortion to be scrapped.

I thought abortion was already decriminalised in the UK?

Technically abortion is illegal in the UK with exceptions. An abortion may be carried out within the first 24 weeks of pregnancy if two doctors agree the mother's mental or physical health would be less damaged by terminating the pregnancy than continuing. Abortions are rarely, if ever, declined within the first 24 weeks if the mother wants one.

Under a few circumstances a pregnancy can be terminated beyond 24 weeks but that is the exception rather than the rule. This can only happen if there is a grave risk to the life or the permanent health of the mother, or if the child would be born with disabilities. In any of those cases an abortion may be carried out until birth.

So what is the change being proposed?

The current suggestion is to decriminalise abortion completely. Launched in February the 'We Trust Women' campaign wants the "abortion time limit to be removed from criminal law".

This would mean anyone could have an abortion for any reason right up until birth.

However on ITV's Good Morning Britain, Dr Suzanne Tyler said there was no evidence to suggest that "decriminalising abortion will increase the number of late terminations".

Why is this controversial?

The 24 week limit was set in 1967 because that was considered the point it was viable for a baby to survive outside the womb. As such it was decided that any point beyond that, a foetus was a person and should not be killed. Due to medical advances since the 60s, several babies have been born before 24 weeks and survived. This has led to calls for the 24 week limit to be cut as viability has changed.

However this proposal would remove the question of viability altogether and scrap any sort of limit.

Critics fear this would allow abortions of perfectly healthy foetuses right up to birth for the convenience of the mother or because they were found to have the "wrong" sex. Labour MP Robert Flello said he was "utterly and completely appalled by this abhorrent proposal" and Democratic Unionist Party MP Jim Shannon called the campaign "absolutely disgraceful".

Christian groups have also waded in to attack the campaign. Nola Leach, chief executive of CARE, said life was precious "from conception" and added that "abortion is not in the best interests of the mother or the unborn child".

Who is running the campaign?

The campaign was first launched by Britain's biggest abortion provider, the British Pregnancy Advisory Service (BPAS). Their "We Trust Women" campaign calls for limits on abortion to be "relegated to history".

One of the most controversial aspects to the row is the decision of the midwives' union, the Royal College of Midwives (RCM), to back the campaign without consulting its members. The union represents almost 30,000 midwives and many have expressed their outrage at the decision.

Fury mounted further after it emerged that Professor Cathy Warwick, chief executive of the union, is also chairman of the abortion provider BPAS. She had been a trustee of the charity for five years but became chairman in 2014 and so carries ultimate responsibility for its strategy.

According to the Mail, which uncovered the link, BPAS has become increasingly political with Warwick as chair and aims to "expand our advocacy for the decriminalisation and destigmatisation of abortion throughout the UK", internal papers revealed.

More than 20,000 have signed a petition on CitizenGo demanding Warwick withdraws RCM's support and consult members before any other formal positions are taken. A statement on the website branded the campaign "extremist" and added: "Only China (that beacon of human rights and dignity), North Korea (another beacon of human rights and dignity), Vietnam and Canada have such permissive abortions laws."

Who has objected?

A number of politicians and charities have expressed their outrage at both the campaign and RCM's decision to endorse it.

Conservative MP and member of the health select committee Andrew Percy said Warwick had a "clear conflict of interest" and added: "It's pretty disgusting."

Crossbench Catholic peer Lord Alton said RCM's support was "shocking". Midwives "who have a high calling – bringing babies into the world" were "being frogmarched into carrying out terminations", he said.

Dr Peter Saunders, chief executive of the Christian Medical Fellowship, said it was "bitterly ironic that the RCM, the supposed champion of safe childbirth and antenatal care, should be backing a campaign seeking to legalise the killing of unborn children up until birth." Saunders called for Warwick to resign and said her duel role was "an extraordinary abuse of power".

Nola Leach from CARE added it was an "absolute disgrace" for RCM to back the campaign. "The RCM is supposed to represent all midwives and many of them are understandably appalled at the stance being taken. What sort of message does the RCM's stance on abortion send to pro-life midwives?

"Midwives are trained to help save lives and to safely deliver unborn babies into the world but now, the RCM is advocating and campaigning for abortion on demand, right up until birth. It is utterly inconsistent."

As well as charities and politicians, a number of individual midwives have also waded in.

Sally Carson, a midwife from Chester said in the Mail: 'Midwives are for delivering live babies wherever possible and trying to preserve the lives of those born prematurely. These babies are not tumours that they can just remove.'

Another midwife Michelle Viney added it was "shocking" RCM did not consult its members.

What do the Royal College of Midwives say?

A statement on the union's website called newspaper reports "distorted and sensationalist". The charity's spokesman said: "This is not about being for or against abortion. It is about being for women and respecting their choices about their bodies."

The statement continued: "Our recent statement on abortion set out our belief that abortion should be removed from the scope of the criminal law. We do not believe that it is right that it is still the case that women who choose to have an abortion can be criminalised and face prison.

"This is a position adopted with the full knowledge and support of the RCM board, which is an elected body made up entirely of registered UK midwives."