The North Dakota Senate approved the most restrictive state ban on abortions on Friday, by passing two measures including one that would bar the procedure as soon as a fetal heartbeat is detected.
Fetal heartbeats can be detected as early as six weeks. A second bill was also passed that would ban abortions based on sex selection and genetic abnormalities.
The bills, which passed the state House of Representatives last month, now head to the governor, Republican Jack Dalrymple, who has not indicated whether he would sign them into law or not.
Several states ban most abortions after 20 weeks of pregnancy. Arkansas lawmakers recently approved a ban on most abortions after 12 weeks of pregnancy that could take effect in August if it survives legal challenges.
The North Dakota "heartbeat" bill provides exceptions if an abortion would prevent the death or irreversible impairment of a pregnant woman and sets up a direct challenge to the Supreme Court's decision in Roe v. Wade that legalized abortion in 1973.
"The impact of 40 years of advancements in medicine and technology cannot be ignored," Republican Senator Spencer Berry said.
"The images and heartbeat from the womb provide strong and overwhelming evidence of - at the very least - potential life," Berry said. "And we have been instructed by the Supreme Court to protect that very potential."
North Dakota has a single clinic that performs abortions, the Red River Women's Clinic in Fargo in the southeast corner of the state, represented by the Center for Reproductive Rights.
At six weeks, the ban would take effect before many women would know they were pregnant, the center said, urging the governor to veto the bills.
"The Supreme Court has said repeatedly that states simply do not have the power to ban abortions before viability," said Julie Rikelman, the center's litigation director. "This is well before viability."
North Dakota senators voted 28 to 15 to ban abortions if a woman is seeking it solely based on genetic abnormalities or the sex of the unborn child.
Opponents argued the Legislature should not get involved in such decisions.