Kristen Bell's 17-month-old daughter can speak sign language!

Los Angeles - Kristen Bell uses sign language to communicate with her daughter.

The Frozen star, who is expecting her second child with husband Dax Shepard, thinks their 17-month-old little girl, Lincoln, is "the smartest baby ever" because she is already talking "a bit" and knows "40-50 signs".

She said: "She signs a lot, which is nice. There's a lot of research to suggest that they will be happier if they can communicate before their verbal scores are developed.

"There's a time when they can understand everything you're saying but their verbal scores don't exist."

She added: "I can talk to her and she'll sign in three, four word sentences which is really amazing. She'll come in the kitchen and be like (signing) 'More crackers please!' And I'm like, 'Yes, okay!' "

She added: "She's MENSA, without a question!? She's the smartest baby ever!"

But the 34-year-old actress admits Lincoln is also already very opinionated.

She told UsMagazine.com: "It's the tantrum stage."

Kristen's second pregnancy is going smoothly and she is grateful her hormones aren't out of control.

She said: "Same as the first one! Really easy, thank God. I've had a lot of friends who have had rough pregnancies and I'm really, really thankful."

Watch Kristen and Dax in this adorable new TV add that highlights why they make the best couple!