The actress – who plays Bella Swann in the vampire film series - was looking forward to her alter-ego having a child with her on-screen blood-sucking lover Edward Cullen but admits the reality was somewhat different because they used an animatronic child, which was operated by a member of the crew.
Speaking of the moment Bella meets her half-vampire, half-human child, Kristen said: "In the book that was one of my favourite parts.
"But filming it, this guy's sweating under your eye line, they get the hand up to touch your face and then it sticks to your hair and pulls a little bit.
"You're like, 'Ugh! Get that thing off me. Get me a baby, this is ridiculous.' It had hair and it's a newborn baby."
Robert Pattinson – who plays the baby's vampire father Edward – was also repulsed by the artificial baby as it looked like something from a horror movie.
He is quoted by the Daily Record newspaper: "It's Chucky from 'Child's Play'!"
Bella and Edward's daughter, who they name Renesmee Carlie Cullen, grows much faster than other children and Kristen admits filming with some of the child stars was tough because they were bigger than her.
The 5ft 6in beauty said: "Occasionally I couldn't pick up the kid."
IrishCentral.com's Top Celebrities: Kristen Stewart