US showbiz website TMZ has reported that Hilary, 23, has lost her starring role in The Story of Bonnie and Clyde.
She had been cast to play the bank robbing heroine (Faye Dunaway's Oscar winning role in 1967) but her pregnancy announcement has caused a major upset in the independent film's planned production schedule.
'Unfortunately, we are now faced with scheduling conflicts with our leads Hilary Duff and Kevin Zegers,' the producers have said.
'We were told that Duff would not be available until June 2012 and that Zegers would not be available until January of the new year. Due to our obligations with investors and international buyers, it is imperative that we stick to our current schedule. Therefore, we are forced to explore other options for the two lead roles."
Director Tonya Holly commented, "We know that she'll be a wonderful mom. So we are really happy for her."
This is Hilary's first pregnancy with Canadian hockey star husband, Mike Comrie. She shot to fame playing Disney's Lizzie McGuire.
Did you lose out to work once you announced you were pregnant?