The highest court in the central Mexican state of San Luis Potosi overturned the one-year prison sentence imposed on Hilda Lopez de la Cruz after she suffered a miscarriage.

"The chamber decided my innocence and all I know is that I am innocent," the 22-year-old told a press conference Tuesday in Mexico City.

Her legal odyssey began in July 2009, when Lopez, then six weeks pregnant, arrived at the municipal hospital in Tamuin, San Luis Potosi, suffering from stomach pains that turned out to be a miscarriage.

Doctors notified the prosecutor's office that it could be an abortion and hurried her away half-naked to the municipal police.

After spending the night in a police lockup, Hilda was released until 2012 when a state judge ordered her arrest for having had an abortion, which is illegal in San Luis Potosi.

Attorneys hired by the reproductive rights group GIRE appealed Lopez's April 2013 conviction to the state Supreme Court, which overturned the verdict, citing lack of evidence.

The prosecution case was based solely on a "confession" doctors extracted from Hilda under duress as she was hemorrhaging.

GIRE's director, Regina Tames, said that between 2009 and 2011 at least 679 Mexican women were accused of abortion by medical personnel without any proof against them.

"That is a substantial increase in recent years," Tames said.

Of Mexico's 32 jurisdictions, only the Federal District - Greater Mexico City - has fully decriminalized abortion in the first 12 weeks of pregnancy.

Elsewhere in the Aztec nation, it has been customary to allow termination of pregnancies resulting from rape.

But some Mexican states, including San Luis Potosi, have adopted laws establishing a right to life starting from the moment of conception. EFE