The "Teen Mom 2" star announced via twitter that she and husband Jeremy Calvery are expecting a baby girl together.
Messer, who already has two daughters with ex-husband Corey Simms, tweeted on Christmas Day "So everyone, Ali and Aleeah are going to have a little sister. That is our Christmas present. Hope you all enjoyed your Christmas!"
The MTV star also posted a collage of photos to show off her baby bump and beau of six months.
In addition to her big baby news, the expecting mom also shared that she got a Pandora bracelet, iPad 2 and gift certificates from her hubby for Christmas, later posting "Above all gifts having my family home making memories we'll never forget has meant the most! #Happy Mommy & Wifey! (: @Calvert505."
What do you think of Leah's announcement? See even more expecting stars in the gallery above!