The US House of Representatives has approved a Republican measure restricting abortion to the first 20 weeks after conception, one of the most stringent pro-life bills in the past decade.

The Pain-Capable Unborn Child Protection Act passed the chamber 228-196, largely along party lines, on Tuesday but the symbolic legislation stands no chance of becoming law in President Barack Obama's administration.

The White House had threatened a veto of the bill on Monday, dismissing it as "an assault on a woman's right to choose".

House Speaker John Boehner, however, praised it as "a strong statement that all life is precious", and he noted that it comes after Kermit Gosnell, a Philadelphia abortion doctor, was convicted for illegally performing late-term abortions in his clinic.

"We have a moral obligation to defend the defenceless, and we will continue to fight to ensure our nation's laws respect the sanctity of unborn human life," he said.

Republicans said the grisly trial of Gosnell served as reminder of why this law was needed.

Involuntary manslaughter

In May, Gosnell was sent to prison for murdering three babies and for the involuntary manslaughter of a patient who died of a drug overdose after she went to Gosnell for an abortion.

A clinic worker testified during the trial that Gosnell had delivered live babies during botched late-term abortions and cut their spinal cords.

Abortion rights groups said Republicans were seizing on the tragic circumstances of Gosnell's victims.

"Their relentless campaign to outlaw abortion will encourage more criminals like Kermit Gosnell," Ilyse Hoguem, NARAL Pro-Choice America's president, said.

"They will not stop until they completely undermine the ability of women to make personal, private medical decisions with their doctors."

The bill, which includes an exemption for women who become pregnant through rape or incest provided they first report the assault to authorities, caused heated debate in the House.

Women included

After being criticised because female House Republicans were not involved in writing or passing the legislation out of the House Judiciary Committee, Republican leaders went out of their way to include women.

Republican Representatives Virginia Foxx of North Carolina and Marsha Blackburn of Tennessee helped manage debate on the bill.

Trent Franks, a long-time abortion-rights opponent and the bill's sponsor, provoked outrage last week when he said in a committee hearing that "incidence of rape resulting in pregnancy [is] very low".



Democrats criticised Franks and Republican supporters of the bill, which also earned six Democratic votes, as being out of touch with women's issues.

Most US states allow abortions to the point when a foetus becomes viable outside the womb, considered to be some 24 weeks of pregnancy.

Ten states have passed laws similar to the Franks bill, and several of them are facing challenges in court.