(Reuters) - A federal judge on Wednesday blocked Ohio from enforcing a new law that critics said would effectively ban most abortions in the state, starting as early as six weeks into pregnancy.

FILE PHOTO: Abortion-rights campaigners attend a rally against new restrictions on abortion passed by legislatures in eight states including Alabama and Georgia, in New York City, U.S., May 21, 2019. REUTERS/Jeenah Moon/File Photo

U.S. District Judge Michael Barrett in Cincinnati issued a preliminary injunction against enforcing the “Heartbeat Protection Act,” saying it imposed an unconstitutional “undue burden” on a woman’s right to obtain a pre-viability abortion.

The law was signed by Republican Governor Mike DeWine in April, following passage by the Republican-controlled state legislature, and was slated to take effect on July 11.

It was designed to stop doctors from performing abortions after a fetal heartbeat can be detected. This can occur six weeks into a pregnancy, before many women know they are pregnant. Under the law, violators could face up to a year in prison.

“Governor DeWine has long believed that this issue would be decided by the United States Supreme Court,” spokesman Dan Tierney said in an email following Wednesday’s decision.

Several other states have also passed “heartbeat” laws, betting that a solid conservative majority on the Supreme Court could eventually overturn Roe v. Wade, the 1973 decision declaring abortion a constitutional right. Judges have blocked similar laws in Kentucky and Mississippi.

In May, the state of Alabama went further, when Republican Governor Kay Ivey signed a law effectively banning nearly all abortions in the state. That law is also being challenged in court.

Ohio’s law was challenged by the American Civil Liberties Union and Planned Parenthood, which said it could end 90 percent of abortions in the state.

The Ohio law includes exceptions for when a woman’s life or health is at risk, but not for rape or incest. Alabama’s law also has no exception for rape or incest.

“Today, the court has upheld the clear law: women in Ohio ... have the constitutional right to make this deeply personal decision about their own bodies without interference from the state,” Freda Levenson, legal director for the ACLU of Ohio, said in a statement.

In his ruling, Barrett said enforcing Ohio’s law would cause irreparable harm to patients by undermining their “well-settled” constitutional right to abortion access.

“To the extent that the State of Ohio is making a deliberate effort to overturn Roe v. Wade and established constitutional precedent, those arguments must be made to a higher court,” he wrote.

The case is Preterm-Cleveland et al v. Yost et al, U.S. District Court, Southern District of Ohio, No. 19-00360.