Jessica Alba

Jessica Alba has opened up for the first time since announcing she and fiance Cash Warren are expecting their first child.

"It’s quite a blessing and perfect timing," she tells Extra in an interview, airing Wednesday, of her pregnancy.

But she says the whole experience has left her feeling more emotional.

"Anything could make me incredibly angry or break down crying," she says. "That’s not something I’m used to.”

Her one fear about mommyhood: Breastfeeding.

She says she recently had a dream and "it had to do with breastfeeding which is the only thing I’m paranoid about. More than giving birth.”

How is she staying in shape during her pregnancy?

"I try to eat as healthy as possible and exercise," she says. "As long as I don’t gain too much, too fast, that’s the key."