North Dakota’s Republican governor signed into law the nation's strictest anti-abortion measures Tuesday, including one "fetal heartbeat" bill that would ban most abortions as early as six weeks into a pregnancy. Gov. Jack Dalrymple is also the first to sign into law a ban on abortions based on gender selection and genetic abnormalities, such as Down's syndrome. The governor said the measures were intended to directly challenge the U.S. Supreme Court's 1973 Roe v. Wade ruling that legalized abortions up until a fetus is visible, which is around 22 to 24 weeks. North Dakota's new measures are likely to be challenged in the courts. Legislators in the state House endorsed three other anti-abortion measures last Friday, two of which would ban abortions after 20 weeks, except in medical emergencies, and require doctors performing abortion procedures to have admitting privileges at a local hospital. State House representatives also approved a ballot referendum, slated to be part of the state's 2014 general election, that would let voters declare that life begins at conception.