Iowa’s Republican-controlled legislature passed the most restrictive abortion ban in the United States on Wednesday, outlawing the procedure after a fetal heartbeat is detected, often at six weeks and before a woman realizes she is pregnant.

The Senate voted 29-17 to pass the House of Representatives-approved bill, according to the legislature’s online voting tallies. The bill now goes to Republican Governor Kim Reynolds, an abortion opponent, who has not said publicly whether she will sign it into law.

The legislation is aimed at triggering a challenge to Roe v. Wade, the U.S. Supreme Court’s 1973 landmark decision which established that women have a constitutional right to an abortion, activists on both sides of the issue said.

Abortion opponents aim to land abortion questions back in front of the nation’s top court, where they believe the 5-4 conservative majority could sharply curtail abortion access or ban it outright.