CHICAGO - Lawmakers in the US state of Iowa approved the most restrictive abortion ban in the country Wednesday, hoping for a national reckoning over the divisive issue.

The Midwestern state’s Republican-controlled legislature approved a ban on most abortions when a fetal heartbeat is detected, which can occur as early as six weeks into a pregnancy. There are exceptions for victims of rape or incest.

Women have been able to legally seek an abortion throughout the United States since 1973’s landmark Supreme Court decision Roe v. Wade. But the right to reproductive choice remains tenuous as debate rages over the issue, especially in areas where conservative Republicans are in power.

The US Supreme Court in 2016 rejected appeals by both North Dakota and Arkansas to preserve similar “heartbeat” laws, which had been struck down by lower courts. If Iowa Governor Kim Reynolds - a Republican who opposes abortion - signs the measure into law, the heartbeat restriction would likely trigger a court battle.

Some of the bill’s supporters had urged its passage as a way to set up a potential US Supreme Court confrontation over abortion.

They believe that President Donald Trump could appoint a conservative justice to the high court in the next few years, tilting its makeup in their favor by the time a court challenge winds through the legal system.

“Today, we are taking a courageous step... to tell the nation that Iowa will defend its most vulnerable, those without a voice - our unborn children,” state legislator Shannon Lundgren said on the state House floor.

The American Civil Liberties Union condemned the bill’s passage, saying in a statement that it would “take Iowa women back nearly a half century.”

“All we can say right now is that we fought this legislation every step of the way and regret that it has made it this far,” ACLU of Iowa’s spokeswoman Veronica Fowler told AFP.

“It is clearly unconstitutional and it effectively blocks the right (to) an abortion for most women,” she said.