A 56-year-old Iowa woman was killed by debris from an explosion at a 'gender reveal' party on Saturday, where a pipe bomb was "inadvertently" created, authorities said.

Gender reveal parties are designed to announce the sex of an expectant couple’s baby by surprising guests with either pink or blue decorations.

Families have become ever more creative with their announcements, and the family in Iowa decided to create an explosion, which would shower coloured powder into the air.

But the celebration went horribly wrong. Pamela Kreimeyer died instantly after she was struck in the head by a piece of metal from the device that was intended to reveal the sex of the baby, the Marion County Sheriff’s Office said in a statement issued on Monday.

Ms Kreimeyer, whose relationship with the unnamed parents is unknown, had gathered with friends in Knoxville, Iowa, to find out whether the baby would be a boy or a girl.