AceShowbiz - Khloe Kardashian is "thrilled to extend her family" after welcoming a son. The 38-year-old reality TV star and her 31-year-old basketball player ex Tristan Thompson, who already have 4-year-old daughter True together, have added to their family with a baby boy born via surrogate and Khloe is over the moon.

"Both baby and mother are very happy and healthy. Khloe is so thrilled to expand her family," a source told Us Weekly. The new baby was conceived in November, before Khloe discovered that Tristan was having a baby with Marlee Nichols in December.

Tristan, who also has five-year-old Prince with ex Jordan Craig, and Khloe have not spoken since, except to discuss co-parenting True.

A source previously told PEOPLE, "Khloe and Tristan are not back together and have not spoken since December outside of co-parenting matters. The baby was conceived via surrogate before it was revealed to Khloe and the public that Tristan was having a baby with someone else in December."

And one of Khloe's close friends, Faye Resnick, recently branded Tristan "disappointing." She told E! News, "I love everything about Khloe and True. Obviously, Tristan was a little disappointing but, aunties and moms and sisters, Khloe and True, it's a beautiful family and we're all just right there."

"It's a village. She is so excited. She is really excited; she's having a baby! True has a little sibling. It's such a good time."