Emily Blunt thinks 'Frozen' triggered her labour.

She said: "I saw 'Frozen' the day before I had my daughter. Isn't that crazy? There was nothing on and I was like, 'Do you think this will be good?,' and John indulged me and we went to see it."

Discussing the film's theme song, 'Let It Go', Emily quipped: "I was like, 'I'm about to. I'm literally about to let it go.' "

The 31-year-old beauty shot 'Into the Woods' while she was pregnant and says filming came at the perfect time for her.

She told E! News: "I was done with the first three months by the time we started shooting.

"I was in the fun time where you're kind of elated and energetic and then I wrapped right before the not-so-fun time where you're sort of enormous and you can't sleep and you pee every 10 minutes."

'Into the Woods' is described as a "dark" tale and Emily thinks it is wrong that some schools only allow the first half of the show - which is more cheerful - to be performed.

She said: "Isn't that wrong? It's not right. Look at all the Disney movies -- Dumbo's mother is chained up and tormented and then Bambi loses his mother and 'The Lion King' when his father gets trampled. I remember being very upset by that, but kids understand.

"This is what these fairy tales are. They're cautionary tales. They're warnings, but also advice to them to say with honesty, 'You're going to have some knocks and they're going be the making of you. But just be careful.' "