(Reuters) - The American Civil Liberties Union, its Ohio branch and Planned Parenthood on Wednesday filed a lawsuit challenging an Ohio law that they say could ban abortion as early as six weeks into a woman’s pregnancy.

The law, which was passed by the Republican-controlled state legislature in April, bans abortions if doctors can detect a heartbeat, which can occur as early as six weeks into pregnancy.

Four other U.S. states have passed similar “heartbeat” abortion bans in 2019 seen as part of a push to overturn the landmark 1973 Roe v. Wade U.S. Supreme Court decision declaring abortion a constitutional right.

“This is a ban on almost all abortions, and if the court does not block it, it will imperil the freedoms and health of Ohio women,” Freda Levenson, legal director of the ACLU of Ohio, said of the law set to take effect July 10.

On Tuesday, Alabama’s state Senate passed the country’s strictest abortion bill, outlawing nearly all abortions other than those to protect a mother’s health.

Anti-abortion advocates know any laws they pass are certain to be challenged, and courts this year have blocked a restrictive Kentucky law and another in Iowa.