Jamie Lynn Spears' mother is reportedly desperate for her youngest daughter to sign a pre-nuptial agreement before she gets married - so she can protect her fortune.

The 17-year-old star - who is expecting her first child with fiance Casey Aldridge - could be forced to sign the contract in a bid to protect her earnings from TV show Zoey 101, reports magazine InTouch.

A source tells the publication, "The contract is already drawn up and ready to go. Lynne's not sure marriage is a good idea, but she'll go along with that if that's what Jamie Lynn wants - as long as Casey signs the contract."

Lynne also ordered eldest daughter Britney to organise a pre-nuptial agreement ahead of her 2004 wedding to Kevin Federline.