Indiana did something unprecedented this week: it sentenced a woman to a 20-year prison sentence for violating a decades-old feticide law.

Purvi Patel's conviction, announced on Monday, is the first American case in which a court has found a pregnant woman guilty of violating a fetal homicide law.

Read more: 14 facts that explain how America regulates abortion

Patel arrived at the St. Joseph Regional Medical Center’s maternity ward in July 2013 with an exposed umbilical cord, bleeding heavily, according to court documents. She had taken off work because of severe cramping. She told doctors that she then had the miscarriage, where she noticed the stillborn fetus among the blood.

Saying she "didn’t know what else to do," she placed the body in a dumpster and went to the hospital.

Patel later told detectives she hadn’t wanted her strict Hindu parents to find out about the pregnancy.

Indiana pursued charges of feticide against Patel: in court, the state argued that she had violated a 1979 law that prohibits violence against fetuses. A jury trial ruled against Patel on Monday, on charges of feticide and child neglect. Patel is now sentenced to a minimum of 20 years — and maximum of 70 — in prison.

Some of the details of the Patel case are still unclear: there are questions, for example, over whether she took abortion-inducing drugs — the drugs that were the basis of her feticide conviction.

Feticide laws exist in most American states, and many have been on the books for decades. Prosecutors have generally used them to pursue more aggressive charges against those who commit violence against pregnant women.

The Indiana case, however, suggests a significantly different use for these laws: to prosecute women who appear to have harmed their own fetuses. Reproductive-health advocates worry this could ultimately prove dangerous for women, who could face possible legal issues, particularly those who miscarry a child.

"Prosecutors in Indiana are using this very sad situation to establish that intentional abortions as well as unintentional pregnancy losses should be punished as crimes," Lynn Paltrow, executive director of National Advocates for Pregnant Women, told the Guardian in August 2014. "No woman should be arrested for the outcome of her pregnancy."

38 states have laws prohibiting fetal homicide

Fetal homicide laws typically recognize a fetus as a legal entity, thus offering protection from acts of violence against a pregnant woman such as domestic violence or car accidents.

"Society may achieve broader social policy goals of curbing domestic violence and assault against pregnant women through use of feticide statutes," Alison Tsao wrote in a Hastings Law Quarterly article on the history of these laws. "Supporters of feticide statutes argue that the focus is not on the fetus, but rather on the pregnant woman who has been 'doubly-harmed.'"

The idea of legal protection for fetuses is centuries old. As one Indiana law professor notes, the Code of Hammurabi from the 18th century BCE provided, "If a man strikes a woman ... so that she loses her unborn child, he shall pay ten shekels for her loss."

The idea shows up throughout the American legal system, too. There are now 38 states that have some version of a fetal homicide law, according to the National Conference of State Legislatures. At least 23 of those states' laws apply to the earliest stage of pregnancies, while others do not take effect until later in gestation. (Many use viability — when the fetus is thought to be able to survive outside the womb, typically around 25 weeks — as the point at which the law takes effect.)

There is also a federal law: the Unborn Victims of Violence Act, passed in 2004, two years after the highly publicized murder of Laci Peterson, a California woman killed by her husband when she was more than seven months pregnant. That law says that anyone who "causes the death of, or bodily injury ... to a child, who is in utero at the time the conduct takes place, is guilty of a separate offense."

These laws typically have specific exemptions for legal abortion, which is protected under the 1973 Supreme Court case Roe v. Wade. Some laws also specifically exempt pregnant women from prosecution under the statutes, meaning that the woman carrying the fetus could not face charges of feticide.

Indiana's law, passed in 1979, does not have such an exemption — allowing the state to bring charges against Patel.

Patel is the first pregnant woman to be convicted of her own fetus’s homicide

Other states have used feticide laws to prosecute those who perpetrated crimes against pregnant women. Tsao, for example, writes about a case of a Missouri man who beat his daughter, who was seven months pregnant at the time. "The fetus was pronounced dead on the day after the beating," Tsao writes. The man was convicted on a charge of second-degree fetal murder.

Patel's case is unique because it's the first conviction of a woman in her own fetus's death — although there is still much that's unclear in the details of the case.

Specifically, there is mixed evidence as to whether Patel committed feticide, which prosecutors charge happen when she took an abortion-inducing drug that she ordered online. But toxicologists didn't find any evidence of that drug in her bloodstream. PRI has written one of the most thorough accounts of the issue:

Prosecutors based the feticide charge on text messages police found on Patel’s phone. They say the messages show she talked to a friend about buying abortion drugs online. But the toxicologist didn’t find any trace of those drugs in her body or in the fetus’ body. And police found no evidence that she actually purchased the drugs.

While Patel is the first woman to be convicted under a feticide law, she isn't the first against whom charges have been pursued.

In 2011, a Chinese immigrant named Bei Bei Shuai (also in Indiana) was charged with feticide after attempting suicide while eight months pregnant. Christine Taylor, a mother of two in Iowa, was charged with attempted feticide when she fell down the stairs at home after an argument with her husband. Charges were eventually dropped in both cases, though Shuai spent some time in prison.

Advocates say this sets a bad precedent for abortion rights and reproductive health

"That has potential for the woman to be charged if there is a miscarriage and the circumstances are unclear," says Elizabeth Nash, senior state issue associate at the Guttmacher Institute.

If women are scared to come forward about complications with a pregnancy, the law poses a serious threat to proper medical care, Nash said.

The Patel case still is not fully settled, and she has indicated she plans to appeal her conviction. Her defense team has argued that the two charges she faces — feticide and neglect of an dependent — are contradictory.

Feticide would require that she had "knowingly or intentionally [terminated] human pregnancy" while the child was still in the womb, while "felony neglect of an dependent" would require that the child had been alive when she abandoned it.