Trent Franks, an Arizona congressman, made the comments at a House of Representatives committee meeting that was exploring a measure that would ban all abortions after 20 weeks without exception.
"The incidents of rape resulting in pregnancy are very low," Franks, who authored the bill, said as he argued against a Democratic amendment to the legislation that would allow exceptions for rape and incest.
"When you make that exception, there's usually a requirement to report the rape within 48 hours and, in this case, that's impossible because this is in the sixth month of gestation and that's what completely negates and vitiates the purpose of such an amendment."
His remarks angered the Democratic members on the judiciary committee while sparking a social media uproar over an enduring hot-button social issue in the United States.
"There's no scientific basis for that. And the idea that the Republican men on this committee can tell the women of America that they have to carry to term the product of a rape is outrageous," said California congresswoman Zoe Lofgren.
There is, indeed, no medical research that suggests rape results in a lower rate of pregnancy. A study by the American Journal of Obstetrics and Gynecology found that more than 30,000 pregnancies result from rape in the United States each year.
With lightning speed, both the Democratic Congressional Campaign Committee and an aide to Nancy Pelosi, the minority leader of the House of Representatives, fired out emails highlighting Franks's remarks.
The brouhaha echoes the one that greeted former Missouri lawmaker Todd Akin last year when he suggested during an interview that a woman's body can shut down after a "legitimate" rape to prevent pregnancy.
Akin failed in his bid for a Senate seat thought to be easy pickings for the party, with Republican strategists blaming his rape comments. Other comments about rape and reproductive issues by Republican politicians were thought to have alienated female voters during the presidential election; 55 per cent of them cast their ballots for President Barack Obama last November.
Franks's bill was given the green light by the judiciary committee along party lines and is expected to make it to the House floor some time next week. Republicans unanimously voted against the Democratic amendment so that the bill's current exemptions only apply when there is a great risk of "death of the pregnant woman" or "substantial and irreversible impairment of a major bodily function."
The Arizona legislator, a staunch social conservative and longtime pro-lifer, said any exceptions could easily be "extrapolated into abortion on demand."
Other Republicans on the committee argued that 20 weeks was plenty of time for a woman, regardless of her circumstances, to determine whether to terminate a pregnancy.
"Even if you reported (the rape or incest) within 48 hours, to wait until 20 weeks to have the abortion performed would be absolutely unacceptable," said Virginia's Bob Goodlatte, the chairman of the judiciary committee.
Lofgren argued that politicians were in no position to understand the difficulties in making such a decision faced by a young girl who's been raped by her father, for example.
Emily's List, an organization that helps elect Democratic women who back abortion rights, said Franks's remarks were in keeping with the party's general philosophy about women.
"The Republican assault on women's rights and opportunities never seems to end," Stephanie Schriock, president of the organization, said in a statement.
"They're supporting the same anti-woman policies that led voters to reject them during the last election, and trying to rebrand themselves with the hope that nobody will notice."
Franks, 55, a longtime pro-lifer who used to wear a tie pin in the shape of the feet of a fetus as an Arizona state legislator, made an attempt to clarify his remarks later in the day.
"My friends on the other side constantly want to try to inject the rape/incest question always into the debate," Franks said. "Just to make clear my point earlier, pregnancies from rape that result in abortion after the beginning of the sixth month are very rare. That’s a matter of fact."
Lofgren replied: "The suggestion that rape rarely leads to pregnancy has no basis in science or fact."
Franks insisted that he had "never made such a suggestion." Goodlatte backed Franks, arguing that few abortions performed after 20 weeks gestation are rape-related.
The legislator has said that his abortion bill was partly prompted by the case of Kermit Gosnell, the Philadelphia abortion doctor recently convicted of first-degree murder for killing three babies after they were born alive.
"We, as a nation, find ourselves at a point at which we don't offer unborn children even the most basic protections — even protections we extend to animals and property," he said earlier this month.
"The trial of Kermit Gosnell exposed late abortions for what they really are: relocated infanticide."