The news comes just weeks after the pretty star announced her engagement to baseball player Cutter Dkystra.
This will be the first child for the couple.
Sigler and Dykstra have been dating for a year and she's clearly smitten. The actress recently told Life & Style magazine, "It's hard for me to find a soundbite about Cutter. I think the one thing I could say and the only thing I will say is that I would wish for any girl in the world to find their Cutter."
The star will be pregnant at the same time as best pal Joanna Garcia, who recently announced she's expecting her first child with her husband, New York Yankees star Nick Swisher."
They're not the only celebrity best friends currently planning babies together - singer Jessica Simpson and her longtime pal CaCee Cobb are both pregnant too.