Ben Affleck's new wife Jennifer Garner has accidentally announced they are expecting a baby girl on US TV show Tonight With Jay Leno.

The Daredevil actress was discussing her pregnancy experiences when she accidentally referred to her baby bump as "she".

Upon realising her gaffe, the star gasped and covered her mouth in horror.

She said: "I have never felt so pregnant in my life. You just start to feel like you're the hugest person on the face of the planet. And I sat there and at first I felt bad because I wasn't helping and then I just felt bigger and bigger like she…"

Garner avoided further questioning by revealing her how much she is enjoying her marriage to Affleck: "It's been obviously exciting and fun, a lot going on."