Donald Trump Jr., Vanessa Trump "So Excited to Add to Our Family"

Vanessa Trump and Donald Trump Jr. attend the 9th annual Dressed to Kilt charity fashion show at the Hammerstein Ballroom on April 5, 2011 in New York City. Credit: Dimitrios Kambouris/

Vanessa Trump and her husband Donald Trump Jr. are thrilled about their latest baby news.

Together since 2005, the couple announced Wednesday that they're expecting their fourth child together.

"We're so excited to add to our family," Vanessa told Us Weekly in an exclusive statement Thursday. "I'm 4 months along . . . the baby is due in October."

Revealing that she and Donald don't yet know if it's a boy or girl, she added, "But we'll find out soon. I'm feeling really good so far! It's been an easy pregnancy."

The Trumps are already parents to daughter Kai, 5, son Donald III, 3, and Tristan Milos, 7 months--and Vanessa says her two oldest are just as thrilled about the news as their mom and dad.

"Tristan . . . doesn't know what's going on," Trump laughed. "But Kai and Donnie are so excited! They're so involved with Tristan and love helping me feed and change him--so they're looking forward to having another baby around!"

Added the La Poshett handbag designer, "We're so blessed to be able to have another child to add to our happy, growing family."