The Cosmopolis star told the crowds at the 2011 San Diego Comic-Con that the scene in question does not shy away from some of the more gory details, HitFix reports.
"I think the birth scene... for a fantasy series that has kind of a youngish audience, it goes very far," Pattinson said. "There was no other way to do it."
Meanwhile, when asked to pick a favourite scene in The Twilight Saga: Breaking Dawn, Pattinson's co-star Taylor Lautner confessed that he was incapable of doing so.
"I've always been able to choose one... But this one I can't. I don't know," Lautner said. "There's so much going on in this movie and all of the characters are dealing with their own little things."
Finally, Kristen Stewart, who plays Bella Swan, revealed that she had difficulty holding the young actress who plays her daughter.
"I couldn't pick up the kid sometimes," Stewart admitted.
Harry Potter star Rupert Grint recently expressed his happiness for Pattinson's success in the Twilight films, claiming that he feels no rivalry with his former co-star.
Stewart was involved in a minor car crash last week when another driver hit the back of her Mini Cooper.
Digital Spy is bringing you exclusive videos, pictures and live panel blogs from Comic-Con all weekend - view our full coverage of the event here.
More Comic-Con 2011 coverage:
> Comic-Con 2011: The best and maddest fan costumes - In Pictures
> Steven Spielberg to make Comic-Con debut with Tintin
> Justin Timberlake "stoked" for Comic-Con 2011
> Sarah Michelle Gellar: 'Actresses should visit Comic-Con floor disguised'
Watch a teaser trailer for The Twilight Saga: Breaking Dawn below: