Pattinson also revealed both her and Kristen felt "vulnerable" when they were shooting the film's sex scenes because they were so many different people on set, most of whom seemed as nervous as the performers.
"The sex scenes were difficult. The set was crazy and you have about 20 people in the room and someone saying things like, 'No, Bella would not have made that noise. Can we do it again?'
"It was very charged, but a very tender and sentimental scene. It's not a scene from the book, so everyone was nervous about doing it right. A ton of other people were nervous.
"And, Kristen and I were both worried about the shape of our bodies would look on camera. We felt vulnerable."
Hype around the film was unbelievable, he said.
"It's strange trying to do a singular event which everyone is expecting. At the end of the day, watching other people have sex is never going to be that spectacular. Hopefully it'll be good. There's so much hype. You're like, 'God, I hope this lives up to it!'"
However, it is not the only scene Robert is nervous about - Kristen's character Bella eventually gives birth to a half-human, half-vampire baby with gory results and the actor says the on-screen labour were "horrible".
He told Total Film magazine: "It was horrible. Insanely graphic and the most nerve-wracking thing about the whole shoot!"
The Twilight Saga: Breaking Dawn - Part 1 will be released in New Zealand on November 17.
- AAP with BANG! Showbiz
