Spears' latest pregnancy has derailed her bid to star as the troubled rocker and frustrated her agents at the William Morris Agency, TMZ.com reported.
Reps were busy working to get her roles, totally unaware that she and her husband Kevin Federline were busy expanding their family, a source said.
"It came as a shock," a William Morris insider said of the pregnancy.
After Spears' condition became public, the role was offered to Lohan, who turned it down, TMZ.com said. Hudson has reportedly become the first choice of producers, but the current status of the film is not known.
Spears has been busy recording and taking care of Preston, her child of seven months with Federline.