After MSNBC broadcast a clip of an interview with Trump's comments, the billionaire rowed back his remarks, first saying that the abortion issue should be handled by states and later adding that doctors who performed abortions, rather than women, should be held legally responsible.
"The doctor or any other person performing this illegal act upon a woman would be held legally responsible, not the woman," Trump said in his final statement. "The woman is a victim in this case as is the life in her womb."
Trump's earlier statements drew heavy fire from abortion rights supporters and opponents alike.
The billionaire businessman has won support from Republican voters for selling himself as a Washington outsider. But he has also come under pressure from conservatives to prove he is one of them on issues such as abortion, and he has drawn criticism for comments that offended women and minority groups.
"There has to be some form of punishment" for women, he said in the MSNBC interview. Asked what form he would advocate, Trump said, "That I don't know."
"Of course, women shouldn't be punished," rival Republican candidate John Kasich said on Wednesday, saying he opposes abortion except in specific cases such as rape. March for Life, an anti-abortion group, said in a statement that women should "consider paths to healing, not punishment."
Abortion rights supporters were equally incensed.
"Just when you thought it wouldn't get worse," Hillary Clinton, the Democratic front-runner, wrote on Twitter. Dawn Laguens of the Planned Parenthood Action Fund, the political arm of the women's health group, called Trump "flat-out dangerous" in a statement.
After the backlash started, Trump's campaign sought to moderate his view. "This issue is unclear and should be put back into the states for determination," Trump said in a statement that was provided to Reuters by email.
Later, he walked back his comments further to say doctors, not women, should be responsible.
MSNBC is expected to air the full interview later on Wednesday.
Abortion has been legal in the United States since 1973, when the Supreme Court declared that a woman's constitutional right to privacy protects her decision to end a pregnancy.
In the decades since the ruling, there have not been enough votes on the Supreme Court to reverse the ruling, but numerous states have passed laws aimed at restricting abortion.
Trump previously outraged many women after he took issue with tough questions at a debate from Fox News' Megyn Kelly. He said Kelly had "blood coming out of her eyes, blood coming out of her wherever," which many saw as a reference to menstruation.
According to a recent Reuters/Ipsos poll in March, 66 percent of all likely women voters said they had an "unfavorable" view of Trump. But among the 460 Republican women who responded to the poll, 62 percent had a "favorable" view of the New York businessman, while 38 percent did not.
Trump has also called illegal immigrants from Mexico criminals and rapists and pushed for a temporary ban on Muslims entering the United States.
Trump's insurgent campaign has revealed discord in the Republican Party. On Tuesday, both Trump and Kasich abandoned pledges to support the party's eventual nominee. U.S. Senator Ted Cruz did not explicitly abandon the pledge but said Trump would not be the nominee.
Cruz as well as Kasich criticized Trump's initial comments about abortion. Cruz said in a statement the billionaire had not thought the issue through and would "say anything just to get attention."
"I think probably Donald Trump will figure out a way to say that he didn't say it or he was misquoted or whatever," Kasich said. "I don't think that's an appropriate response."
