San Salvador, El Salvador - When Maria Teresa Rivera suffered a miscarriage three-years ago, she was handcuffed to a hospital bed, surrounded by seven policemen, charged with murder and sent to jail.

Rivera is among hundreds of women believed wrongly jailed in El Salvador for defying a ban on abortion, accused of inducing abortions when in fact they suffered miscarriages, stillbirths, or pregnancy complications, women's rights groups say.

After a trial lasting eight months, 30-year-old Rivera was sentenced to 40 years imprisonment for aggravated murder - the longest sentence ever imposed on a woman in the Central American nation for an abortion crime.

She is one of 17 women, all jailed for more than 30 years, that human rights groups are campaigning to set free.

"The judge didn't believe me when I told him that I didn't even know I was pregnant at the time and that I'd started bleeding at home and had a miscarriage," Rivera said from Ilopango women's prison on the outskirts of the capital, San Salvador.

I thought about my young son who'll be nearly 50 by the time I'm released... My son won't know me when I leave jail. - Maria Teresa Rivera

"I'll never understand why he was so harsh. I thought about my young son who'll be nearly 50 by the time I'm released... My son won't know me when I leave jail."

No abortion allowed

Abortion in El Salvador has been illegal under all circumstances since 1998, even in cases of rape, incest, a deformed foetus, or when a women's life is in danger.

El Salvador is one of 28 countries globally that prohibits abortion in all circumstances, according to the Centre for Reproductive Rights.

Rights group Amnesty International says this outright abortion ban is a leading cause of maternal mortality because it forces women to undergo dangerous back-street abortions.

The ban in El Salvador has led to 129 women being prosecuted for abortion or aggravated murder, of which 26 were convicted of murder and imprisoned, according to the Citizen Group for the Decriminalisation of Therapeutic, Ethical and Eugenic Abortion (CFDA), a local rights organisation.

The campaign to free the 17 women by CFDA and international human rights groups has highlighted the impact of El Salvador's abortion law on women, who in many cases are already young single mothers, from poor backgrounds and with little education.

Wealthier women can travel abroad for abortions in private clinics but El Salvador's healthy ministry estimates there are 6,500 clandestine abortions in El Salvador every year, and 11 percent of women and girls who have undergone a clandestine abortion have died, according to the World Health Organisation.

Last year the plight of "Beatriz", an ill, 22-year-old rural woman from El Salvador carrying a malformed foetus, sparked global outcry when the high court upheld the abortion ban, even though her life was at risk and the foetus unlikely to survive.

After a legal battle lasting months that escalated to the Inter-American Court of Human Rights, the El Salvadoran court finally relented and Beatriz underwent a Caesarian section and survived the operation. Her baby lived only a few hours.

El Salvador is now facing increasing pressure from the United Nations, the Inter-American Court on Human Rights, and rights groups to amend its abortion law and release women jailed on abortion crimes.

Women covered in body paint protest the criminalisation of abortion outside San Salvador's Supreme Court [Reuters]

'Baby killer'

Ilopango women's jail, tucked behind a busy suburban street, was originally built to house 220 inmates but now has nearly 2,000 prisoners, making it El Salvador's most overcrowded jail.

Rivera, who has served three years of her prison sentence, will never forget her first night behind bars. She slept on the bare floor and when the lights went out at 10pm inmates chanted "baby killer" as she lay awake until dawn.

"Ending my life did cross my mind then," said Rivera, a single mother and former garment factory worker, whose son now lives with his grandmother.

The only glimmer of hope for Rivera and the other 16 women is the campaign to set them free spearheaded by Dennis Munoz, an El Salvadoran human rights lawyer working for CDFA.

In May, on behalf of CFDA and international rights groups, Munoz submitted a petition to local lawmakers seeking a pardon for the 17 imprisoned women and their release. All other legal avenues had been exhausted in their cases.

Munoz said their convictions are based on flimsy medical evidence, flawed trials and inconsistent judicial rulings.

"I'm known as the abortion lawyer, the one defending 'child murderers' as the right-wing press here has branded these women," Munoz said outside the jail gates.

"What motivates me is to help poor people, who have the right to a good lawyer, and get innocent people out of jail. If this was my daughter, I wouldn't want her to suffer for a crime she didn't commit."

El Salvador's Supreme Court is considering the petition with a decision expected within weeks. Eight of 15 judges would need to rule in favour of the women for them to be released, and President Salvador Sanchez Ceren would need to agree.

If all other legal mechanisms in El Salvador fail, the cases of the 17 women could be taken before the Washington-based Inter-American Commission on Human Rights, Munoz said.

"I've told them I can't promise to get you out of jail or that I'm going to win. But I will put up a fight, and a good fight," said Munoz, who has secured the early release of eight women jailed for abortion crimes since 2007.

Powerful Catholic Church

Munoz is aware that a big part of his fight means coming up against a powerful conservative lobby in the country's congress, and an influential Roman Catholic Church and evangelical groups, who are all determined to maintain the outright abortion ban.

Here social and cultural norms are based on religious values, and not on a right-based approach. - Mario Soriano, medical doctor

They say the rights of an unborn child, which are enshrined in El Salvador's constitution, should be protected by law at all costs, from the moment of conception.

Opposition conservative lawmakers, as well as the left-wing ruling FMLN party, fear easing the abortion ban would come at a political cost as it could alienate voters and the church.

"Some kind of election takes place every 18 months in El Salvador so it's difficult to make progress on the abortion issue because politicians worry decriminalising abortion will mean losing votes," Munoz said.

With the issue of abortion an entrenched part of El Salvador's political battleground, few government officials are willing to publicly favour changing the abortion law.

Mario Soriano, a medical doctor who heads the adolescent development programme at El Salvador's health ministry, is a rare voice calling for change, in favour of easing the country's abortion law.

"Here social and cultural norms are based on religious values, and not on a right-based approach," Soriano said.

"Religious values often outweigh clinical ethics, as well as the law being applied incorrectly, which means you can get doctors denouncing women of inducing abortions and then calling police to the hospital."

For Rivera her only source of solace is reading the bible at the prison church.

"I pray to God for this to end soon. I just want to be with my son and tuck him into bed. I was an orphan - and now my son is too," she said.

This article first appeared on the Thomson Reuters Foundation news service