WASHINGTON -- Hundreds of protesters rallied at the Indiana statehouse on Tuesday in opposition to restrictive abortion measures that would, among other things, require doctors to tell pregnant women about a controversial theory that says having an abortion could lead to an increased risk of breast cancer.

House Bill 1210, introduced by Indiana state Rep. Eric Turner (R), would make abortions illegal after 20 weeks. The Senate has already passed a similar bill, but it is awaiting action in the House.

The bill would also require physicians to inform a pregnant woman seeking an abortion that the fetus could feel pain and require patients to view an ultrasound. A patient could get out of doing so only if she stated her refusal in writing.

Turner was not available for comment on Wednesday, but he recently said, "The vast majority of both the Senate and House are pro-life legislators, and I think we truly represent Hoosier constituents."

But one of the most controversial portions of the bill is the part that would require doctors to inform women about the risks of abortion, including "the possibility of increased risk of breast cancer following an induced abortion and the natural protective effect of a completed pregnancy in avoiding breast cancer."

Indiana wouldn't be the first state to promote this theory. According to the Guttmacher Institute, five states -- Alaska, Mississippi, Oklahoma, Texas and West Virginia -- currently include mentions of a link between abortion and breast cancer in written counseling materials.

In 1999, Nevada Republican Sharron Angle -- who was then in the state Assembly and recently lost the U.S. Senate race against Harry Reid -- proposed a similar measure requiring doctors to make the abortion-breast cancer link.

The American Cancer Society (ACS) and other major health organizations, however, have rejected this theory. In February 2003, the U.S. National Cancer Institute brought together "more than 100 of the world's leading experts who study pregnancy and breast cancer risk." They found that neither induced nor spontaneous abortions lead to an increase in breast cancer risk. In fact, the risk is actually increased for a short period after a woman carries a pregnancy to full term (i.e., gives birth to a child). According to ACS, these findings were considered "well established," which is the highest level for scientific evidence.

In June 2009, the highly respected American College of Obstetricians and Gynecologists Committee on Gynecologic Practice wrote, "Early studies of the relationship between prior induced abortion and breast cancer risk were methodologically flawed. More rigorous recent studies demonstrate no causal relationship between induced abortion and a subsequent increase in breast cancer risk."

"I think that the pregnant lady needs to have every bit of information that she can," Turner said in defense of the strict counseling requirements in his bill. "I think it's important that she see an ultrasound image of her child before she elects to have an abortion. She can see that it's a living being."

While some backers of the anti-abortion legislation turned out on Tuesday in Indianapolis, the Indianapolis Star reported that they were greatly outnumbered by opponents.

For Planned Parenthood of Indiana (PPIN), which organized the rally, the fight is personal. House Bill 1205 would prohibit the state from "entering contracts with or making grants to any entity that performs abortions or maintains or operates a facility where abortions are performed." While many pieces of legislation in Indiana don't take effect until July 1, after the close of the legislative session, this bill has an emergency provision -- meaning it would take effect immediately upon passage.

Planned Parenthood has 28 locations around the state. According to PPIN President Betty Cockrum, they serve 9,300 patients on Medicaid for a wide range of services including administering pap tests and STD treatment, providing birth control and giving annual exams. At PPIN's other eight funded health centers, they serve 12,500 Medicaid patients. So if House Bill 1205 passes, PPIN estimates that approximately 21,800 Hoosiers would be affected.

Indiana is also central in the national debate on abortion rights. On the federal level, Rep. Mike Pence (R-Ind.) is leading a similar campaign against the national family planning organization.

"We're working as hard as we can to have the right conversations with legislators and leadership," said Cockrum in an interview on Wednesday with The Huffington Post, adding that on the national level, one of their primary targets is Sen. Richard Lugar (R-Ind.). "I have to believe that Sen. Lugar is going to understand that taking family planning dollars away from existing health care providers to pay for birth control and pap tests isn't good public health policy." Indiana Right to Life, which supports Pence's bill, also considers him a key vote. It recently sent an e-mail message to its supporters encouraging them to contact Lugar.

Indiana Right to Life has hailed 13 measures introduced into the state legislature this session, calling it the "largest array of pro-life legislation in recent history." The group's website states, "The flood of legislation is a direct result of the dramatic change in leadership at the Statehouse following the November elections."

For now, these bills are all stalled. Indiana's House Democrats left the state on Feb. 22 in order to prevent their Republican colleagues from reaching the quorum needed to push through anti-union legislation.