Iowa's Republican-controlled legislature advanced a bill that would ban most abortions in the state as early as six weeks into pregnancy.

The state's Senate passed a bill late Tuesday in a 32 to 17 vote and is now headed to Republican Gov. Kim Reynolds' desk for signing, after she ordered a special legislative session with the sole purpose of restricting the procedure in the state.

The bill prohibits physicians from providing most abortions after early cardiac activity can be detected in a fetus or embryo, commonly as early as six weeks into pregnancy, before many women know they are pregnant.

The bill includes exceptions for miscarriages, when the life of the pregnant woman is threatened and fetal abnormalities that would result in the infant's death. It also includes exceptions for pregnancies resulting from rapes reported within 45 days and incest reported within 140 days.

The Senate vote came despite Democratic backlash after the state House voted 56-34 largely along party lines to advance the measure following a roughly 12-hour day that saw the measure move through rounds of consideration and debate.

"The voices of the unborn and their elected representatives will not be silenced any longer! Congrats to the Iowa House and Senate!" Reynolds tweeted early Wednesday upon the bill's passage.

She is expected to sign the legislation into law on Friday, according to a statement from her office. The law would go into effect immediately following Reynolds's signature.

However, while the bill language makes clear it is "not to be construed to impose civil or criminal liability on a woman upon whom an abortion is performed in violation of the division," guidelines on how physicians would be punished for violating the law are left up to Iowa's board of medicine to decide -- leaving the potential for some vagueness in how the law ought to be enforced in the interim.

"There may or may not ever be rules promulgated," said Iowa Senate President Amy Sinclair, a Republican, amid several questions from Democrats on the floor. There were no legal penalties for physicians added in the bill, she said.

"As far as clarity, this is about as clear as mud," Democratic state Sen. Molly Donahue said on the floor.

Reynolds' move to push for abortion restrictions in Iowa comes weeks after Iowa's Supreme Court declined to lift a block on the state's 2018 six-week abortion ban, deadlocking in a 3-3 vote whether to overturn a lower court decision that deemed the law unconstitutional.

The new bill and its 2018 predecessor are nearly identical. However, the latter was not enacted immediately, granting the board of medicine time to flesh out how it planned to administer the law.

Ruth Richardson, President and CEO of Planned Parenthood North Central States, previously said the legislation "would have a devastating impact on patients and communities in Iowa," as abortion procedures are currently legal up to 20 weeks in the Hawkeye state.