"I had no idea. It looked in the mirror like I'd drunk too many beers," Contactmusic quoted her, as saying.
Jovovich, who is due any day now, said that it was almost six and a half weeks before she realised that she was pregnant.
"It was almost six and a half weeks before I put two and two together, which was funny because my belly was getting big," she said.
The actress is currently engaged to writer/director Paul W. S. Anderson, with whom she is expecting her first child.
She has already revealed that the couple are expecting a baby girl.