Vanessa Hudgens popped the blood vessels in her face while filming a scene where she goes in labour.
The 24-year-old star, who plays a teenage mother Apple Bailey in her forthcoming film 'Gimmie Shelter', felt both physically and mentally exhausted when she was in character.
She told E! News: "Probably the most physical and emotionally draining scene was my birthing scene. I've never shot a birthing scene and I ended up popping blood vessels in my face."
Vanessa formed a strong connection with her alter ego and even found herself feeling strange when Apple's baby was taken away from her after they completed scenes for the movie.
She explained: "It's odd, it really is. I mean, I totally had a connection with my baby - my movie baby - and I just had so much love for her but afterwards they call 'cut' and take the baby away and I'm just left there hanging."
The brunette beauty piled on the pounds for the part but found it harder to lose weight afterwards, despite doing plenty of exercise.
She said: "Getting it off was the more difficult part. It was a lot of exercise ... Just doing a lot of cardio, a lot of yoga and just really anything active."
Although Vanessa found the role demanding she enjoyed the experience because it forced her to push herself.
She explained: "Every single day was definitely a challenge but one I embraced with open arms. "It was just so thrilling to be able to push myself every day and see how far I could take it."