Louisville, Kentucky - Outside Kentucky's last abortion clinic, anti-abortion rights protesters gather each day to face off against orange-vested volunteers who escort women inside for a procedure that state politicians have increasingly sought to restrict in recent years.

But now, abortion opponents are backing a new "fetal heartbeat" bill proposed in the Kentucky legislature - the most restrictive yet, and one being considered in other US states - that they hope will do more than ban abortion as soon as a heartbeat can be detected.

Similar laws have been declared unconstitutional - including in Iowa, where a state judge on Tuesday struck down a 2018 fetal heartbeat measure for violating the state constitution.

But supporters of such bills in Iowa and Kentucky and elsewhere say they are aiming for appeals and legal challenges to reach a conservative-leaning US Supreme Court in hopes it will help overturn the 1973 case of Roe v Wade, which blocked states from prohibiting abortion before viability.

"Roe v Wade being overturned would be wonderful - I hope it does happen," said Donna Durning, as she prayed, holding anti-abortion literature, next to an "Abortion is wrong" sign at the EMW Women's Clinic in Louisville.

181205083314165

The American Civil Liberties Union (ACLU) sad outlawing abortion any time after a fetal heartbeat can be detected, about six weeks into a pregnancy, is unconstitutional and would effectively ban the procedure.

Court shifts to the right

Similar laws have been introduced in a handful of other states including Ohio, Missouri, North Dakota and Florida. North Dakota's 2013 law was struck down by a federal judge. The Supreme Court has not yet taken up the issue.

Kentucky's Senate majority leader, Damon Thayer, has said he "would be proud if it is Kentucky that takes it up to the Supreme Court and we change Roe v Wade". Governor Matt Bevin has called himself an "unapologetically pro-life" Republican. Several abortion cases are currently making their way through federal appeals courts.

Trump's election and his appointment of two conservative-leaning justices - Neil Gorsuch and Brett Kavanagh - have emboldened politicians in some states to pursue restrictive measures, which have ranged from onerous regulations to bans on second-trimester abortions, according to the Guttmacher Institute, a reproductive rights non-profit think-tank.

170326125731442

"Many state lawmakers continue to consider and enact abortion bans that fly in the face of constitutional standards and Roe's precedent in anticipation of an eventual lawsuit on such a ban coming before a Supreme Court hostile to abortion rights," the group said.

In Kentucky, several restrictive laws passed by the Republican-controlled legislature have been blocked amid legal challenges, including requiring women to get an ultrasound before an abortion and a ban on a common second-trimester abortion procedure.

Last fall, a federal judge struck down a Kentucky law requiring abortion providers to sign advance agreements with hospitals and ambulance services for emergency patient care, in a ruling that kept the state from revoking the license of EMW Women's Clinic, Kentucky's only remaining abortion clinic in a state that once had 17.

Under the proposed fetal heartbeat bill, introduced by Republican Robert Goforth, doctors could be charged with a felony for performing an abortion in cases where a fetal heartbeat can be detected.

"When that baby's heart's beating, you have to recognise that is a life there," Goforth said in a statement earlier this month.

But the ACLU and others said many women don't even realise they are pregnant at six weeks.

Dr Nicole Nolan, an OB-GYN resident in Louisville, said the decision should be made between the patient and her physician. She said the bill would harm women who learn their babies cannot survive outside the womb. "This bill would hurt these women and hurt their families," she told Al Jazeera.

181209052459657

Tamarra Wieder, public affairs director for Planned Parenthood of Indiana and Kentucky, also opposes the bill at a recent state capitol news conference.

"For years now Governor Bevin and his friends here in the legislature have been racing to make Kentucky the first state in the nation without abortion access, and now elected leaders see a new prize at the finish line - the end of Roe," she said.

It's far from clear that the high court would overturn the ruling.

The court has consistently ruled that states may not ban abortion before fetal viability, which is when a fetus could survive outside the womb, thought to be about 24 weeks.

In Iowa on Tuesday, District Court Judge Michael Huppert stated in his ruling striking down the Iowa law that the earliest cardiac activity was detectable well in advance of fetal viability. Supporters of the law vowed to appeal.

Abortions at their lowest rate in years

Three years ago, the Supreme Court rejected a request to hear challenges to hear an appeal over North Dakota's heartbeat bill, leaving in place lower court rulings that blocked those laws.

2014918659818403

Some legal experts have downplayed the chance for a full reversal of Roe v Wade and instead argued that the conservative-leaning court could allow states greater leeway to enact regulations on abortion.

The debate comes as the US Centers for Disease Control and Prevention reported last year that abortions were down to the lowest rate since 1973. The agency said the total number of reported abortions decreased by 24 percent between 2006 and 2015, from 840,000 in 2006 to 638,000 in 2015.

Guttmacher Institute has cited a mix of factors are at work, including better access to contraception and improvements in women's reproductive health

Back at the clinic in Louisville, Louisville clinic escort Meg Stern said her group will keep supporting access to Kentucky's only clinic as long as it is open.

"We know abortion is a normal and safe part of reproductive care and look forward to a day that the Kentucky legislature ceases pointless attacks on bodily autonomy which are obvious wastes of lawmakers' time and taxpayer's dollars," Stern said.