Vanessa and Nick Lachey are expecting a baby girl

Nick tweeted a picture with the words "It's a girl" written in the sand on a beach, and said it was a great way to celebrate their third wedding anniversary.

He wrote: "Can't think of a better way to celebrate 3 years of marriage to my beautiful @VanessaLachey than this! #family"

The couple got married in 2011 after five years of dating, and welcomed son Camden into the world in September 2012.

They recently admitted they wanted to add to their family, and Nick had said he would love to have a daughter - although she will have her work cut out for her to be as well-behaved as her big brother.

Nick previously said: "We won't wait too much longer. I really want to have a little girl ... Cam's got the best temperament ever, we can't imagine having a better kid than we do. He's an angel."