The actress, who plays Julie Carp in the Weatherfield soap, is said to be expecting her third child with filmmaker husband Chris Jupe.
Coronation Street Blog reports that Cavanagh is due to give birth in the spring of next year.
She and Jupe are already parents to Noah, 8, and Jemma, 5.
The real-life development leaves Coronation Street producers in an awkward situation, as they will be unable to write her pregnancy into the storyline.
Cavanagh's character Julie had her ovaries removed earlier this year after a growth led to a false result on a pregnancy test.