SALMON, Idaho (Reuters) – The Idaho Senate on Monday approved a measure requiring women seeking abortions to undergo an ultrasound before ending a pregnancy, joining a number of states passing ultrasound measures to discourage abortions.

      The bill now heads to the state House of Representatives, where it was expected to pass.

      Idaho’s Republican Governor, C.L. “Butch” Otter has not yet said whether he would sign the bill into law and a spokesman declined to comment on Monday.

      Otter said last April, after signing a measure banning abortions after 20 weeks of pregnancy, that he supported restrictions on abortion.

      Idaho is among 10 states considering a form of ultrasound legislation, said Elizabeth Nash, state issues manager for the Guttmacher Institute, an abortion-rights think tank.

      A law recently passed in Virginia goes into effect in July, which will bring to eight the number of states requiring pre-abortion ultrasounds, she said.

      The bill moving through Idaho’s legislature is modeled after a Texas law which requires abortion providers to show or describe to a woman an ultrasound image of her fetus.

      That 2011 law went into effect last month after withstanding a challenge in federal court.

      Like the Texas measure, which is considered the most restrictive in the nation, the bill in Idaho offers women the option of declining to view ultrasound images or listen to the fetal heartbeat.

      The legislation would subject abortion providers who do not sign and date a statement about the particulars of the ultrasound and women’s responses to it to disciplinary actions or civil penalties.

      Supporters of the measure, sponsored by Assistant Senate Majority Leader Chuck Winder of Boise, said it provides another layer of protection for a woman seeking to terminate her pregnancy.

      “It provides the opportunity for her to learn all the important facts before making this life-changing decision,” according to a statement by Right to Life of Idaho.

      Opponents argue that most women seeking abortions in Idaho will be forced to undergo an invasive “vaginally administered” procedure.

      The majority of abortions are performed before 10 weeks of pregnancy, when an image of the fetus can only be captured through an internal exam, pediatrician and Democratic state Representative John Rusche, said in a statement.

      “The practitioner then needs to record the gestational age and fetal heart rate if present. That info can really only be determined by the ‘internal’ study,” he said.

      Virginia considered but ultimately decided against requiring an invasive vaginal probe after strong criticism from women’s groups and abortion rights supporters, who said it would be demeaning to women.

      The ultrasound measure passed the Idaho Senate in a 23-12 vote mostly along party lines.

      Idaho and five other states in the past two years have enacted late-term abortion bans based on controversial medical research suggesting a fetus feels pain starting at 20 weeks of gestation.

      Idaho’s 20-week ban and a 1972 law making it a felony for a woman to end her own pregnancy, are being challenged in federal court.

      (Editing by Dan Whitcomb and Greg McCune)