The Warm Bodies beauty, 27, announced her engagement to Webber earlier this month (Aug13), and now her representative reveals they are set to become parents.
The spokesperson tells UsMagazine.com, "Teresa is expecting. She and Mark are over the moon excited and can't wait to add to their family."
Palmer began dating the Snow Day actor last year (12), months after suffering a bad break-up.
The child will be Palmer's first, while Webber is already dad to a young son with actress Frankie Shaw.