US House of Representatives Votes to ban abortion after 20 weeks of pregnancy

The Republican-controlled US House of Representatives has voted to ban nearly all late-term abortions after 20 weeks of pregnancy, advancing a priority held by President Donald Trump's party.

Trump is a backer of the Pain-Capable Unborn Child Protection Act, and the White House has said he would sign the measure should it pass Congress and reach his desk.

The bill is not viewed by the Senate as a priority, and its future in the upper chamber remains uncertain

The legislation allows for criminal and civil penalties against doctors or others who perform the procedures, including up to five years in prison.Exceptions would be made in cases of rape, incest or where the life of the mother is at risk.

Republicans cited scientific research by pro-life organizations saying fetuses are able to feel pain from the 20th week after conception. "We cannot claim ignorance. Their pain is no longer invisible to us," House Speaker Paul Ryan told the chamber before the vote.

"We cannot as a society -- with good and upright conscience -- ignore it."

The vote was largely along party lines, 237-189, with all but three Democrats opposing the measure and all but two Republicans in support.

Democrats blasted the bill as a "another shameful attack" on women's rights. "By restricting women's access to safe and legal abortion, Republicans are depriving millions of women across the country of their fundamental right to make the health care decisions that are best for them and their families," Democratic National Committee chief executive Jess O'Connell said in a statement.

According to pollster Gallup, last May 29 per cent of Americans supported the right to abortion under any circumstances, while 50 per cent supported it under certain circumstances and 18 per cent believed all abortion should be illegal.

The US Supreme Court affirmed the right to abortion nationwide in 1973, in a landmark decision which noted the operation could be conducted before the fetus reaches "viability," the point at which it could live outside the womb.

No specific number of weeks was set, but the consensus at the time was placed at between 24 and 28 weeks.