Donald Trump Jr. and Vanessa Trump

Donald Trump Jr. and his wife Vanessa announced that they are expecting their fourth child via Twitter Wednesday.

Donald Trump Jr. and wife welcome another baby boy

"Well, Vanessa & I have some good news we are expecting baby num 4 in the fall!!! Kai, Donnie, & Tristan can't wait!" When a fan later tweeted at Trump, "Didn't you just have one?" he responded, "Yea they'll be 13 months apart, Irish twins!"

Trump and his wife, who wed in 2005, have three other children: daughter Kai Madison and sons Donnie John III and Tristan Milos.