Georgia’s Republican governor on Tuesday is expected to sign a bill outlawing abortion if a doctor can detect a fetal heartbeat, part of a concerted effort to restrict abortion rights in states across the country.


Governor Brian Kemp praised the bill when it passed the state legislature in March and has scheduled a signing ceremony at 10 a.m. ET (1400 GMT), which would make him the fourth governor to sign such a law since mid-March.


Anti-abortion campaigners have intensified their efforts since Donald Trump was elected president and appointed two conservative justices to the U.S. Supreme Court, hopeful they can convince the right-leaning court to re-examine the landmark case Roe v. Wade that established a woman’s right to an abortion in 1973.


Kentucky, Mississippi and Ohio have passed heartbeat laws recently, and Iowa passed one last year. Courts have blocked the Iowa and Kentucky laws, and the others face legal challenges. The American Civil Liberties Union of Georgia has vowed to sue to stop this law.


Even so, anti-abortion advocates have seized the political and judicial opening in their favor, introducing measures in 15 states to ban abortion as early as six weeks into a pregnancy, according to Rewire.News, a site specializing in the issue.


That has raised concerns among abortion-rights advocates about expanding “abortion deserts,” described as major cities that are at least 100 miles (160 km) from an abortion provider.


Between Georgia and Mississippi is Alabama, where the House has passed a bill that would ban all abortions unless the mother’s life was threatened and the Senate is likely to vote on it this week, raising the prospect of a giant abortion desert in the Southeast.


Ushma Upadhyay, professor of reproductive health at the University of California, San Francisco, said she was concerned for low-income women who lack the means to travel.


“This is basic health that should be available to all women regardless of where they live, how much money they make or how many children they have,” Upadhyay said.


Abortion-rights supporters see the heartbeat bills as virtual bans because fetal heartbeats can be detected as early as six weeks, when women may not be aware they are pregnant.


Georgia’s Living Infants Fairness and Equality (LIFE) Act would permit later abortions in medical emergencies. In cases of rape or incest, the woman would be required to file an official police report.