According to Amnesty International, María Teresa Rivera, who already had a five-year-old child, did not know she was pregnant.
The mother-of-one was taken ill at a factory where she worked - and, later, was found by her mother-in-law, bleeding on the bathroom floor.
María was rushed to hospital for urgent medical attention, but, while she was there, a member of staff reported her to the police.
Shortly afterward, police officers arrived and began questioning her without a lawyer present - and arrested her.
In July 2012, María was tried and found guilty of aggravated homicide, despite serious flaws in the evidence against her.
She was sentenced to 40 years in prison - and her young son will be 45 years old by the time she is freed.
So why did this happen?
María lives in El Salvador, where the laws against abortion are some of the strictest in the world.
The act of terminating a pregnancy is illegal in all circumstances, even when the pregnant woman isn't a woman at all but a girl, or when she's a rape or incest victim, or when her life or health is at risk.
Women's rights advocates have said that María is just one of many women who were unjustly imprisoned after experiencing miscarriage, stillbirth, and other obstetric complications, because the Salvadoran constitution declares that life begins at conception.
Now human rights campaigners are pushing for the women to be pardoned, saying they were convicted without sufficient evidence.
The reproductive and sexual health organisation RH Reality Check has started a petition urging U.S. Secretary of State John Kerry to put pressure of the president of El Salvador to issue the pardon.
Will you be signing it?