Heigl also fears she was so "completely bonkers" that her work on the movie may have suffered.
She says, "Most of filming new movie Life As We Know It was a blur. I had just become a mom. I still don't necessarily always know what I am doing, and I certainly didn't then.
"I was all over the place. I was really trying too hard. I was completely bonkers. If I spread myself too thin, I'm not a good actor, I'm not a good mother, and I'm just really high-strung. Then everybody hates me."
Heigl stars alongside Josh Duhamel in the comedy, about two acquaintances who are forced to raise their mutual friends' baby when they are killed in a sudden car accident.