Mum-to-be Ashlee Simpson is so desperate to give birth to her first child, she may induce labour, according to her big sister Jessica Simpson.

The heavily pregnant singer and her Fall Out Boy rocker husband Pete Wentz are set to welcome their first child into the world at any time.

And the star - who reportedly was due to give birth two weeks ago - is gearing up to have her labour induced, says her pop-turned-country star sister Jessica.

In an interview with U.S. chat show host Ellen DeGeneres, Simpson says, "They're going to have to (induce). It's already developing really quick."

And the concerned sister revealed her younger sibling has tried a whole range of wacky tactics to bring on the baby.

Simpson explains Ashlee has tried "different foot massages and stuff", adding: "I don't know. I think she's really just jumping around trying everything right now."