Matthew McConaughey and his wife Camila Alves welcomed their third child together, Us Weekly reports. \nMatthew McConaughey's so skinny! See other celebs who transformed their body for movie rolesAlves gave birth to a baby boy on Friday in Austin, Texas.Though they've been together since 2006, McConaughey and Alves didn't tie the knot until June. A few weeks later on July 4, the actor announced his wife's pregnancy on Twitter.Photos: Everybody's posing nude! Check out Rihanna and other stars who've bared allThe couple are already parents to Vida, 2, and Levi, 4.