US woman dies after boxing match

A female boxer has died in America from head injuries sustained in the ring.

College teacher Becky Zerlentes died on Sunday and is believed to be the first woman to die in a sanctioned bout.

The preliminary cause of death was "blunt force trauma to the head", but results from an autopsy were not immediately available.

Zerlentes, 34, was struck by opponent Heather Schmitz and, despite wearing protective headgear, fell unconscious during the amateur bout in Denver.

Physicians at the Golden Gloves competition jumped into the ring, but Zerlentes never regained consciousness and died several hours later.

Zerlentes had won a regional Golden Gloves title in 2002 before taking a break from boxing.

USA Boxing, which sanctions the amateur sport in America, lifted its ban on women in 1993 and has 2,200 registered as participants.

Women's boxing has increased in popularity in America in recent years, thanks in part to the success of boxers like Muhammad Ali's daughter, Laila, and the Oscar-winning film Million Dollar Baby.