Midwives ruling will drive many from the medical profession, pro-life campaigners say.

But others have welcomed the move by five justices at the Supreme Court in London to overturn an earlier ruling by the Court of Session in Edinburgh helped clarify the limits of conscientious objection in abortion treatment.

Mary Doogan, from Garrowhill, Glasgow, and Connie Wood, from Clarkston, East Renfrewshire, have been in dispute with their employers NHS Greater Glasgow and Clyde (NHS GGC) for several years, which both women claiming they should be involved in delegating, supervising and supporting staff involved in the procedures or providing care to patients during the process.

The case before Lady Hale, Lord Wilson, Lord Reed, Lord Hughes and Lord Hodge centred on the scope of the right to conscientious objection under the Abortion Act 1967, which provides that "no person shall be under any duty ... to participate in any treatment authorised by this Act to which he has a conscientious objection".

NHS GGC's appeal said the right to abstain should only extend to treatment ending a pregnancy, and that was both women were employed as labour ward co-ordinators at the Southern General Hospital in Glasgow this did not extend to them.

The Supreme Court upheld the appeal.

Paul Tully, general secretary of SPUC, said the decision "sadly makes it likely that senior midwives who refuse to kill babies will be forced to leave the profession".

He added: "This will affect anyone who objects to abortion, of any religion or none. It will create a second-class status in midwifery for those who only deliver babies and don't kill them.

"The court has used the opportunity to decide that the conscience clause in the Abortion Act does not apply to General Practitioners and that hospital doctors asked to prescribe abortion drugs will not be covered by the conscience clause.

"We anticipate that this will lead to renewed efforts by health officials to force doctors who have a conscientious objection to abortion either to compromise their respect for human life or to leave the profession.

Archbishop Philip Tartaglia of Glasgow said: "This was never a case about the rights and wrongs of abortion. Nor was it a case about religion. Rather it was a case that centred on the right of ordinary citizens to have their conscience respected in society and at work. All of society is a poorer, less respectful and less tolerant place as a result of this decision."

In the original ruling against them, the judge, Lady Smith, found that the women were sufficiently removed from involvement in pregnancy terminations to afford them appropriate respect for their beliefs.

Announcing the Supreme Court's decision, deputy president Lady Hale said that "participate" in her view meant taking part in a "hands-on capacity".

Lady Hale said the decision on the meaning of the conscience clause "will then set a limit to what an employer may lawfully require of his employees".

National Secular Society executive director Keith Porteous Wood said: "Had the case gone the other way, it might have opened the way for the broadening of conscience clauses in many other areas of life, much to the detriment of those who don't share the religious or ethical views of those exercising their conscience."

Spencer Fildes, chair of the Scottish Secular Society, said: "The Supreme Court ruling was a victory for common sense over religious zealotry.

"Concepta Wood and Mary Doogan sought to extend that opt-out in a way which would sabotage the ability to access safe abortion care for thousands of women. In doing so they placed their religious beliefs above their duty to care for their patients."

Ann Furedi, chief executive of the British Pregnancy Advisory Service (BPAS), also welcomed the ruling and said: "BPAS supports the right to refuse to work in abortion care, not least because women deserve better than being treated by those who object to their choice. But the law as it stands already provides healthcare workers with these protections."