A new law signed by Utah's Republican Gov. Gary Herbert would require doctors to tell pregnant women who chose to undergo medically-induced abortions that the abortion could be halted halfway through.

The bill claims a woman could continue her pregnancy successfully should she not take the second of the two Mifepristone pills that trigger a medical abortion, and instead take the hormone progesterone.

The only evidence of this working is based on a single, widely contested study of six women conducted in 2012 and described as "anecdotal" by doctors.

Herbert signed the Utah bill Saturday, two days before a similar bill passed by the Indiana House of Representatives was thrown out in the Senate without a vote. Members of Indiana Congress opposing the bill, including anti-abortion senators, expressed concern over giving women conflicting information about medical abortions.

The Utah bill will go into effect in May, unless it is challenged in court. A spokesperson for Herbert told BuzzFeed News that the governor would not comment on any laws until after he reached the bill-signing deadline Wednesday night.

“It’s very concerning that legislatures would be forcing doctors to say anything to a patient, but particularly forcing them to give information about a treatment that is completely unproven,” Daniel Grossman, a professor in the department of obstetrics, gynecology, and reproductive sciences at the University of California at San Francisco, told BuzzFeed News when the Indiana legislature was first introduced.

Co-sponsored the legislation Republican Utah Rep. Keven Stratton, told the Deseret News that the law intended to provide women with the information they need, and that he thought it had bi-partisan appeal. “If you’re pro-choice, I would say that it helps you be educated in making the choice,” Stratton said. “If you’re pro-life, it gives an opportunity to look at the options if a decision is made to reverse course.”

Starting in 2015, similar "abortion reversal" legislation has been introduced across the US. Arkansas and South Dakota signed them into law, and a bill is being considered in North Carolina. A similar bill was killed in a House committee in Colorado, and an abortion reversal law was repealed in Arizona in 2016 after Planned Parenthood challenged it in court.

Planned Parenthood did not immediately respond to requests about whether they will challenge the Utah law.

Nearly one third of women in the US seeking first trimester abortions choose medical abortions, that's about 2.8 million since the drug was approved in 2000. It is often favored due to the privacy of taking the pill in your own home rather than undergoing an invasive surgical abortion, and if often easier to access than abortion clinics, especially in medically underserved, rural areas.

To undergo a medical abortion a woman takes mifepristone, then a second drug called misoprostol a day and a half to three days later. The second pill opens up the cervix and causes the contractions of the uterus that expel the pregnancy.