Young American mother Caitlin Coleman and her baby are among dwindling number of Taliban-held US hostages

Among the last of the American hostages held by Islamist militants is a woman who used to be one, but is now two.

One-time Pennsylvania rsident Caitlin Coleman, 30, was kidnapped along with her 32-year-old Canadian husband Joshua Boyle in 2012 while the two were travelling through Afghanistan. Coleman was pregnant, and has given birth in captivity.

All eyes have turned to the little family in the wake of the accidental killing of American hostage Warren Weinstein in US drone strike, revealed this week by the White House.

"I would ask that my family and my government do everything that they can to bring my husband, child and I to safety and freedom," Coleman, wearing a burka, says in the video recording released by their Taliban captors over a year ago.

Boyle, far thinner than when he vanished and wearing a white shirt, adds: "We request from our governments to do what is necessary to bring our families together to safety and freedom."

Bizarrely, Boyle was married for a short time to a first wife, Zaynab Khadr, whose family has links to al-Qaeda, according to the Globe and Mail.

After 9/11, four of Khadr's teenage brothers were arrested as al-Qaeda suspects in Pakistan and Afghanistan. One of them is still serving time in a Canadian prison after ten years at Guantanamo.

The FBI has asked for information about the family's location but is not offering a monetary reward, ABC reports. But with some thawing of relations with the Taliban, the US has made recent moves to negotiate the release of hostages, sources have told the Daily Beast.

As for Canada, the government has been "pursuing all appropriate channels to seek further information and officials are in close contact with Afghan authorities," according to a government statement.