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Baby Mama star Amy Poehler is about to be one herself.

The Saturday Night Live regular, 36, and her husband, Will Arnett, are to become first-time parents, their rep Lewis Kay confirms to PEOPLE.

The baby is due in late fall.

The couple have been married since 2003.

This has been a big week for Poehler. Baby Mama, costarring Tina Fey, landed in the No. 1 box-office spot this weekend, and her Nickelodeon show, The Mighty B, also debuted.

Arnett, 37, is currently shooting the big-screen comedy When in Rome with Kristen Bell.