Ellen Page doesn’t court controversy, it simply lands in her lap. The pint-sized 20-year-old Canadian actress played a paedophile-punisher in the 2005 shocker Hard Candy, a movie that infamously climaxed with a castration scene so gruesome that some viewers were sent screaming for their vomit buckets. At this year’s Sundance Film Festival a screening of her movie An American Crime had to be halted when an audience member fainted at repeated moments of ritualised violence (Page plays a victim of extreme domestic abuse). Her latest movie, Juno, has a light and often whimsical approach to the subjects of teenage pregnancy and teen abortion that is likely to send certain sections of the media into a tailspin.

“I sometimes think that people need to just calm the f*** down,” says Page, staring at the remnants of her freshly consumed five-star burger and fries. She is dressed in blue jeans, black T-shirt with bare feet, and is suitably pixie-like and, at just over 5ft, completely adorable in a Polly Pocket kind of way.

She is also nursing flu and is on antibiotics. “When I signed on to do Juno,” she continues, “A producer said to me, ‘It’s about teen pregnancy? Are you ready for everything that will come with this in the press?’ And I was like, ‘What the f*** are you talking about?’ So, my reaction is basically, ‘I’m glad that these movies provoke you. But really, you all need to calm down!’ ” Page, who was last seen dashing through walls and dodging Vinnie Jones as Kitty Pryde in X-Men 3, adds that the role of the sardonic pregnant teen Juno MacGuff is actually one of the lightest and sweetest parts she’s played. “It’s much simpler to be tortured on camera or to be filmed losing your mind,” she says. “Whereas a script that has characters who are honest, witty and genuine, like this one, is often much harder to act.”

The genius of Juno, of course, is not just that it’s honest and witty, but that the film takes the hoary premise of unwanted pregnancy (see this year’s Knocked Up and Waitress) and transforms it into something entirely new. Here, working from a densely literate script by Diablo Cody (aka the author and blogger Brook Busey-Hunt), Juno depicts a world of dead-pan comic exchanges where the news of Juno’s pregnancy is greeted with bemusement rather than ire by her unflappable parents, where the decision to procure a hasty abortion is rejected in favour of playing surrogate mom for a local wealthy couple (played by Jason Bateman and Jennifer Garner), and where that same surrogacy eventually tests the emotional mettle of all involved and teaches Juno some tough lessons about the transience of love.

Along the way the dialogue bristles with a comic lexicon that was created by Cody and works exclusively for the movie – thus Juno is called a “fertile myrtle” and a “cautionary whale”. She refers to her foetus as a “sea monkey”.

“I took one look at the script and it was like, ‘If this isn’t done right, or if it feels contrived or forced, this whole movie will suck,’ ” Page says. Thankfully, the combined talents of Page, Cody and the director Jason Reitman ( Thank You For Smoking) have made Juno both a critical smash (it was the hit of Toronto) and a sleeper hopeful for next year’s Academy Awards. In the meantime, Page says that she’s just glad that it might help to alter prevalent public perceptions about her gloomy teen screen persona.

A native of Halifax, Nova Scotia, and the daughter of a graphic designer father and teacher mother, Page has been acting since the age of 10, when a talent scout came to her school and cast her as the horse-loving Maggie Maclean in the movie Pit Pony (and the spin-off TV series). Despite nearly a decade of solid film and TV work, it wasn’t until she strapped a creepy paedophile, played by Patrick Wilson, to a table and proceeded to perform an impromptu castration, in Hard Candy, that the film world took notice. The offers came rolling in and Page played a teen junkie in Mouth to Mouth, a traumatised teen in The Tracey Fragments, and a battered and abused teen in An American Crime.She says, perhaps unsurprisingly, that Hard Candy is still the role that sticks in people’s minds.

“I went back-packing through Eastern Europe recently, and even there people would recognise me from Hard Candyand come over to me and say, you know...”

What, leave my balls alone? “Yeah, [sigh] men always make those ‘funny’ jokes. And I say, ‘Oh I’m sorry that there’s one film where a man gets abused, whereas the amount of films I’ve seen where women get raped is enormous! Jesus! Deal with it!” She gives a little shrug and adds, by way of a final defence, “And anyway, if you’ve seen the movie, you’ll know that I don’t even cut off his balls!”

After snagging her key role in the X-Men franchise, Page’s Hollywood status was established and will no doubt be cemented when she appears opposite Dennis Quaid and Sarah Jessica Parker in the upcoming romantic comedy Smart People. And although she still has a “place” in Halifax, she says that she’s currently of no fixed abode, although she might move to Brooklyn this year. In the meantime, she says that she avoids the Tinseltown party scene like the plague and is busy preparing her next role – as a (very) hairy lesbian in the werewolf movie Jack and Diane. And if we think that a lesbian werewolf movie sounds a tad controversial, well, Page knows exactly what we can do about it. Deal with it!

Juno is the Film on the Square Gala on Tuesday, 8.30pm, OWE2 and Oct 31, 3.30pm, OWE1 at The Times BFI London Film Festival. It goes on release on Feb 1 (www.timesonline.co.uk/lff)

Editor's choice

• Burning Bush with W
• Revolution at the new Saatchi Gallery
• Boy George on sex, drugs and Amy Winehouse