Kristen Bell felt ''pressured'' to find the perfect name for her unborn child.

The 'Frozen' star - who already has a 17-month-old daughter Lincoln with her husband Dax Shepherd - is expecting her second child with the 39-year-old actor and confessed the pair struggled to come up with another moniker.

She told People magazine: ''It's a lot of pressure, especially because we felt 'Lincoln' was so perfect.''

Fortunately, the pair have managed to settle on an idea just in time as the latest addition to their family is due ''sometime soon'' - although Kristen was keen to keep the name under wraps.

She said: ''We had a little bit of a breakthrough. We've settled on one, thankfully.''

Meanwhile, the 34-year-old actress recently confessed her daughter is ''the smartest baby ever'' because she is already talking and learning sign language.

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!''