The actress gave birth to her second child in September and waited a month to share the baby news with fans and followers.
She has posted a photo of herself and her baby boy on Instagram, adding the caption: "Happy 1-Month Birthday to our baby boy, Matthew! He has inherited his dad's brown hair and his mom's desire to be carried around all day in a baby sling. He's a good boy."
Ellie and her husband, Michael Koman, are also parents to three-year-old son James Miller.
She announced she was pregnant in June.