If a girl younger than 16 gives birth and won’t name the father, a new Mississippi law — likely the first of its kind in the country — says authorities must collect umbilical cord blood and run DNA tests to prove paternity as a step toward prosecuting statutory rape cases.

Supporters say the law is intended to chip away at Mississippi’s teen pregnancy rate, which has long been one of the highest in the nation. But critics say that, although the procedure is painless, it invades the medical privacy of the mother, father and baby. And questions abound: At roughly $1,000 a pop, who will pay for the DNA tests in the country’s poorest state? Even after test results arrive, can prosecutors compel a potential father to submit his own DNA and possibly implicate himself in a crime? How long will the state keep the DNA on file?

Republican Gov. Phil Bryant says the DNA tests could lead to prosecution of grown men who have sex with underage girls.

“It is to stop children from being raped,” said Bryant, who started his career as a deputy sheriff in the 1970s. “One of the things that go on in this state that’s always haunted me when I was a law enforcement officer is seeing the 14- and 15-year-old girl that is raped by the neighbor next door and down the street.”

But Bear Atwood, legal director for the American Civil Liberties Union of Mississippi, said it’s an invasion of privacy to collect cord blood without consent of the mother, father and baby. She also said that an underage girl who doesn’t want to reveal the identity of her baby’s father might skip prenatal care: “Will she decide not to have the baby in a hospital where she can have a safe, happy, healthy delivery?”

The law took effect July 1 but hasn’t been used yet. Cord blood samples would have to be taken immediately after birth, and the state medical examiner is setting administrative rules for how the blood will be collected and stored. Megan Comlossy, health policy associate for the National Conference of State Legislatures, said she thinks Mississippi is the first state to enact a law authorizing the collection of blood from the umbilical cord — a painless procedure — to determine paternity.

Bryant’s staff says the idea for the law came from public meetings conducted by the governor’s teen pregnancy prevention task force — a group that focuses mostly on promoting abstinence.

Statistics put the state’s teen pregnancy rate among the highest in the country. In 2011 — the most recent year for which statistics are available — there were 50.2 live births in Mississippi per 1,000 females ages 15-19, according to the Centers for Disease Control and Prevention. The nationwide rate was 31.3.

And more than half of Mississippi’s 82 counties reported at least one pregnancy by a 10- to 14-year-old girl in 2011, according to an Associated Press analysis of state statistics.

The governor said he worked with Attorney General Jim Hood, a Democrat, on the cord blood bill. The final version passed the Senate unanimously and the House 98-17. The issue of cost received little debate.

The bill’s main sponsor, Republican state Rep. Andy Gipson, said the U.S. Supreme Court has ruled that DNA left on objects, such as saliva on a disposable cup, can be tested as evidence in a criminal case. He said he thinks umbilical cord blood fits that description.

Democratic state Rep. Adrienne Wooten voted against the bill, saying it will mostly hurt poor women and could lead a prosecution “fishing expedition to find out who the father is.”

“I think that that is totally outside the boundaries of what we as a Legislature should be doing,” said Wooten, who, like Gipson, is an attorney. “We already have laws that deal with statutory rape.”

The attorney general’s office doesn’t keep statistics on the number of cases that district attorneys pursue in Mississippi under the state’s longstanding statuary rape law, spokeswoman Jan Schaefer said.

“A lot of DAs and judges don’t want to take these cases on,” Bryant said. “Oftentimes, the female doesn’t want to press charges or the parents do not want to. So, we’ve just got to stop this.”

The new law says it’s reasonable to think a sex crime has been committed against a minor if the baby’s mother won’t identify the father or lists him as unknown, or if the identified father disputes paternity, is 21 or older, or is deceased. The law says health care workers and facilities cannot face civil or criminal penalties for collecting cord blood, and failure to collect is a misdemeanor offense. The law doesn’t address whether the mother can refuse blood collection or what would happen to her if she does.