In the wedding scene Stewart wears a Carolina Herrera wedding dress and in the birth scene ... well, let's not get into too much detail.
Surprisingly, the 21-year-old Stewart found the wedding and birth scenes equally beautiful.
"It's pretty gnarly, I know," Stewart, recalling the scene where Swan gives birth, says during an interview in Beverly Hills. "I find it grotesquely beautiful.
"I loved it even though there was blood everywhere.
"I have never viewed the baby as a demon, but everything that makes the scene horrifying to others, I find beautiful.
"I was really moved in a motherly way."
What? The scene, to be watched by millions of teenage girls devoted to the Twilight franchise, could be the best advertisement for reducing teenage pregnancy, but did Stewart really think it was beautiful?
"I think some experiences awaken things inside of you," Stewart explains.
"I love animals, but I'm the youngest in my family so I have never had an inclination toward babies, but instantly the idea of it being yours, it is so different.
"It is what I really loved about Bella in this. It was so simple, raw and feral. It wasn't anything complicated. It was just so human and I really loved that."
It is a sure bet that Twilight fans will fill theatres around the globe to watch Breaking Dawn, the penultimate chapter, with the final instalment arriving in November 2012.
The first three films grossed US$1.8 billion ($2.3 billion) worldwide in cinemas, sold more than 25 million DVDs in the US alone and transformed Stewart, Robert Pattinson (Cullen) and Taylor Lautner (Black) into three of the highest-profile and highest-paid actors in the world.
They will earn US$12.5 million per movie for the final two Twilight films. On top of that they will pocket 2.5 per cent of each movie's box office gross, a huge sum considering both movies should tally up more than US$500 million in receipts.
While the birth scene made Stewart a little clucky, the wedding scene also made her glow.
A fan of the Twilight books, Stewart has been looking forward to shooting the scene where she walks down the aisle from the moment she read Meyer's description in the book.
"That scene is what we have been building to for four years," Stewart says.
"It is kind of the most important thing in the whole movie. We shot it at the end and I really got a full experience.
"I think about it as something that happened to me, rather than something I made.
"Usually when you think about scenes you remember what you are going through and the choices and conversations you have with the director. That day was so intense."
Talk of babies and weddings should heighten talk about her reported real-life romance with co-star Pattinson, but Stewart describes the relationship she has with Pattinson - and her other co-star Lautner - as being "just very, very, very good friends".
"I have something really special with both of them that really couldn't have been gotten without an experience like this," she says.
"It doesn't always happen. Just because you have a good experience with an actor, sometimes you finish a movie and you say 'We have to see each other' and then you go 'Wow, we know each other very much within that'.
"That's not what we have. We got lucky and I think maybe it shows. That's why we had such a good time working together."
Stewart smiles, attempting to fully explain the relationship she shares with Pattinson and Lautner.
"Those guys are ... ," she says, pausing for a moment. Her mind is attempting to find the right words and eventually she comes up with two words.
"They're mine," Stewart says.
Lowdown
Who: Kristen Stewart
What: The Twilight Saga: Breaking Dawn - Part 1
When: Opens at cinemas Thursday
- AAP / TimeOut
