North Dakota became the nation’s most restrictive state on abortion rights on Tuesday as Republican Gov. Jack Dalrymple signed a measure banning the procedure if a fetal heartbeat can be detected.

Dalrymple signed two other abortion bans Tuesday that were approved by the state’s GOP-led legislature.

The first would ban abortions based on genetic defects like Down syndrome – the first such measure in the country – and on gender selection. The second would require that any doctor performing abortions in the state be a physician with hospital-admitting privileges.

Dalrymple said in a statement that the bill is a direct challenge to the Supreme Court’s 1973 Roe v. Wade decision, which legalized abortion until a fetus was considered “viable” – usually between 22 and 24 weeks.

“Although the likelihood of this measure surviving a court challenge remains in question, this bill is nevertheless a legitimate attempt by a state legislature to discover the boundaries of Roe v. Wade,” Dalrymple said. “Because the U.S. Supreme Court has allowed state restrictions on the performing of abortions and because the Supreme Court has never considered this precise restriction ... the constitutionality of this measure is an open question.”

Fetal heartbeats can be detected as early as six weeks into a pregnancy, making the North Dakota law the earliest abortion ban in the nation. Previously, Arkansas held that title with a 12-week ban passed earlier this month. The measure prohibits most abortions when a heartbeat can be detected using an abdominal ultrasound.

The North Dakota bill is one of a spate of anti-abortion measures the state legislature has pushed so far this year. Lawmakers last week passed a resolution defining life as beginning at conception, which would essentially ban abortion in that state.

The passage of the measures in North Dakota and Arkansas comes months after an election season highlighted by fights over abortion.

Senate Republican candidates in Indiana and Missouri were favored but lost their races after statements about rape and abortion.