The actress reprises her role as the hapless, unlucky-in-love Bridget for the third film in the franchise, reuniting onscreen with Colin, who plays Mark Darcy, and appearing alongside series newcomer Patrick, who portrays the British actor's new love rival, Jack Qwant.

The movie follows the three characters as they try to figure out who Bridget's baby daddy is, and Renee reveals the cast members were all kept in the dark until the very end of filming to avoid any plot leaks.

"They never actually wrote the ending in the script. I guess you gotta go out of your way to keep a secret these days!" Renee told U.S. breakfast show Today. "They just had a bunch of Xs and Ys (to conceal the identity of the baby's father in the script), and on the day that they shot (the reveal scene) they just moved men and babies around!"

The role marked Renee's Hollywood comeback after a six-year acting hiatus, and she revelled in the chance to return to a character she identifies with, although she harboured some nerves.

"She's so familiar in so many ways and it was such a happy reunion because I love this character and I love playing her," she gushed. "It is so much fun, and to be back with everybody, all my friends, on the set, I mean, heaven!

"(But) also a little terrifying because it's been a while, (you have to) get back in the saddle, and you just don't want to mess it up because I have so much affection for her (Bridget) and I recognise that she holds a lot of meaning for a lot of people."

However, there was a part of the film's plot Renee initially wasn't a fan of, after discovering one scene involved Bridget reaching her goal weight - and she took director Sharon Maguire to task.

"Who doesn't love the extra plate of spaghetti...?" questioned the 47-year-old, who is no stranger to having her own changing looks criticised. "I wasn't sure about that, actually, because I never thought she had a weight issue, I thought that was just something, like all of us, you think, 'Oh, I'd love to change this thing about myself', when in fact, nobody else notices it but you.

"It's that thing about ruminating and self-criticism and all of that, but I had long conversations with Sharon Maguire, the director, about that, and she said, 'No, in deciding how we show that she's evolved, let's let her have that one thing that she's always obsessed about, that she's always presumed was the golden ticket to her happiness, and let it have no bearing on her life at all'. I kind of liked the message in that."