At least 30 ultrasound bills were considered in 17 U.S. states this year, said the Guttmacher Institute, an abortion-rights research group.
Oklahoma lawmakers this year reversed Democratic Gov. Brad Henry's veto to approve making ultrasounds mandatory at least an hour before abortion procedures.
Ohio and South Dakota are now among 14 other states with looser laws calling on doctors to allow women to chose whether to have an ultrasound prior to an abortion, Stateline.org reported Wednesday.
Anti-abortion activists say women should be able to see the most up-to-date medical data about their pregnancies prior to having an abortion.
Pro-abortion activists argue the laws are unnecessary and get in the way of a decision that should be made by patients and doctors.
"Requiring doctors to perform ultrasound on all women at all stages of pregnancy is degrading and cumbersome," Dr. Dana Stone of Oklahoma City said.