Britney Spears' marriage to Kevin Federline has cost her up to $45 million in lost earnings, according to court papers. The prenuptial agreement Spears signed with Federline before they married in 2004 stated she expected to earn $143 million by 2009.

But she has made just a fraction of that after putting pop to one side so she could have two children with the former dancer, 14-month-old Sean Preston and eight-week-old Jayden James.

She has not released any original material or toured since 2003, and her lawyers estimate she has lost between $20 million and $45 million in the past two years. Spears' accounts still appear healthy - she has a $125 million fortune including property worth $15 million and forest land in her native Louisiana worth $6 million.

The singer served Federline with divorce papers last week, ending their brief, turbulent union.

(This news article provided by World Entertainment News Network)