Blake Lively and Ryan Reynolds reveal they're expecting their fourth baby

Blake Lively and Ryan Reynolds are expecting their fourth child as the actress debuted her baby bump on the red carpet at the 10th annual Forbes Power Women's Summit.

Lively was all smiles when she showed off her bump in a gold sequined mini dress.

The couple, who try to keep their family life private, already have three children together - James, seven, Inez, five and Betty, two - and have gushed about parenthood in rare interviews.

"My husband and I chose a profession and a side effect of that is your personal life is public," Lively previously told Marie Claire UK.

"Our child hasn't had the opportunity to choose whether or not she wants her personal life to be public or not. So in order to give her as much normality as possible, we want her to have a childhood like we had."

Reynolds also told E! News how both stars have embraced every twist and turn with love, humour and patience.

"There have been times where I woke up, literally had no idea I had been walking for five minutes," Reynolds previously said.

"But you love it. You wake up in the middle of the night, you got a big stupid smile on your face. I was telling someone else that. Anything else that woke you up every 45 minutes, you'd kill it. But when it's a baby, it's the best thing that ever happened to you."

Congratulations Blake and Ryan!