She was sad that she has to leave her adopted baby Naleigh home while she's filming the movie with her baby co-star.
Actress Katherine Heigl was left heartbroken on the set of new romantic comedy "Life as We Know It" - because she was spending more time with her baby co-stars than her own daughter Naleigh.
The blonde beauty adopted little Naleigh last September but she was forced to spend time away from home to shoot the movie soon afterwards - and the early separation proved to be a difficult one for the star.
She tells Harper's Bazaar magazine, "I was working with these gorgeous little triplets who play my child, (and) I was feeling bad I was spending more time with them than with my own kid. And that broke my heart."
Heigl stars alongside Josh Duhamel in the upcoming film, about two acquaintances who are forced to raise their mutual friends' baby when they are killed in a sudden car accident.