Gov. Laura Kelly vetoed Monday scientifically challenged legislation that would require doctors to tell women taking an abortion pill that the medication's effects can be reversed.

The Kansas bill was modeled on legislation passed in several other states after a California physician produced a report that suggested high doses of progesterone could help recover a pregnancy without birth defects.

Anti-abortion proponents of the bill embrace the report, which excluded patients and wasn't reviewed by an ethics board. The results have been challenged by medical professionals.

"This unwarranted legislation will create confusion and could be harmful to women's health," Kelly said. "The practice of medicine should be left to licensed health professionals, not elected officials."

Mary Kay Culp, executive director of the powerful lobbying group Kansans for Life, said it is "ridiculous to paint the protocol as untested." Culp said 61 percent of abortions in Kansas now involve the pill, and Kelly's veto is a disservice to women who take the pill.

"Women seeking abortion must not be denied current medical information that can save their babies," Culp said.

Republicans arranged a last-minute deal to bring the bill forward before entering into a three-week break, passing it with enough support to consider an override of the Democratic governor's veto.

Women who choose to have a medication abortion first take mifepristone, which stops the fetus from growing, followed within 48 hours by misoprostol, which forces expulsion of the pregnancy.

The legislation, which passed 85-35 in the House and 26-11 in the Senate, would require physicians to tell patients the first drug isn't always effective in ending a pregnancy and may be reversed if the second pill hasn't been taken.

"If Gov. Laura Kelly believes that women should have the right to choose," said Senate President Susan Wagle, R-Wichita, "she should fully support this legislation, which provides women with more information, allowing them to make an informed decision regarding their pregnancy."

House Majority Leader Dan Hawkins, R-Wichita, said Kelly's veto proves "her allegiance lies with Planned Parenthood and the abortion lobby, not with unborn Kansans."

The veto sets the stage for another partisan battle when lawmakers return in May, adding to a list that includes Medicaid expansion and tax cuts.

If Republicans succeed in overriding Kelly's veto, physicians who fail to provide a reversal notice would face a misdemeanor citation, and subsequent violation would be a felony. Facilities must post a "conspicuous sign" with the message in lettering no smaller than 3/4-inch boldface type. Failure to post the sign would result in a $10,000 daily fine.

Daniel Grossman, an OB-GYN professor at the University of California, San Francisco, said there is no evidence the reversal treatment is more effective than doing nothing. Grossman has reviewed research on the subject and co-authored an article on "Legislating without Evidence," published in October by the New England Journal of Medicine.

"The only thing we can say definitively is there is no high-quality evidence documenting the safety and effectiveness of this treatment," Grossman said.

Proponents of the reversal say progesterone has been prescribed for years to help women avoid miscarriages, but Grossman said the drug is administered for specific reasons and usually stopped late in the first trimester.

"It's not commonly used the way they have been advocating for it for the so-called reversal treatment — where it's started very early in pregnancy and continued all the way up until near term," Grossman said. "I don't have a lot of safety concerns, but I think we still need to collect data on this and prove for certain that it is a safe treatment."

Grossman said conclusions reached by George Delgado, a California physician who claimed a study of 754 patients showed a 64 percent reversal rate, was flawed in part because the study relied on ultrasound tests to prescreen patients for the viability of the pregnancy. The study doesn't say how many women were excluded from treatment.

If a woman has a viable baby two days after taking the first pill, Grossman said, she likely will have a normal pregnancy anyway.

The reversal process "is not what I would call a completely crazy idea," Grossman said, but lawmakers shouldn't force a doctor to tell the patient about a treatment that is unproven.

"That's not the way medicine works — that we get a good idea and then we just start doing it and pass laws encouraging patients to use that treatment," Grossman said. "Instead, every good idea actually needs to be tested, and we need to verify that the treatment is safe and effective. I'm really concerned that we're going about this in a way that just runs contrary to the practice of medicine."

Mitchell Creinin, an OB-GYN professor at the University of California Davis, is conducting a registered clinical trial that could be the first source of scientifically sound data on the effectiveness of the reversal.

Women who plan to have a surgical abortion are given the first abortion pill, followed by the reversal drug or a placebo. Creinin plans to publish results next year after learning the rate at which the reversal works.

"The legislation becomes fake legislation when it is based on fake science," Creinin said. "If someone wants to legislate it, then let's make sure it's based on sound science."