Vanessa Manillo Lachey, Nick Lachey

The Lachey family will soon have another member!

Nick and Vanessa Lachey announced Tuesday — their third wedding anniversary — that they're expecting a baby girl, who will join big brother Camden, 22 months.

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"Can't think of a better way to celebrate 3 years of marriage to my beautiful @VanessaLachey than this! #family," Nick tweeted Tuesday, along with a picture of "It's a girl" written in the sand.

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