It comes after a rep for the star confirmed the exciting news just last month, telling E! News, "We can confirm True will have a sibling who was conceived in November", and adding, "Khloe is incredibly grateful to the extraordinary surrogate for such a beautiful blessing. We'd like to ask for kindness and privacy so that Khloe can focus on her family."
While fans were curious about what this meant for the on-again-off-again couple, a source later told People Magazine the Good American co-owner and Thompson are not back together and will continue to co-parent as they have done with their daughter.
The insider said the reality star does not see herself as "a single mum", and wants her ex-boyfriend "as involved as possible" with the baby and the couple's eldest child, 4-year-old True.
"Just like they do with True, Khloé will co-parent the baby with Tristan," the source said. "Tristan is the dad, and Khloé wants him involved as much as possible. He is great with True."
The source added, "She has a great support system with a lot of help. She feels very lucky".
Kardashian and Thompson officially called it quits in December after the Chicago Bulls player cheated on the reality star multiple times, including his most recent infidelity, which was captured in the latest season of Hulu's The Kardashians.
While filming for the reality show, cameras caught the moment the reality star found out Thompson had cheated on her and fathered a child with another woman again.
Opening up during The Kardashians Disney FYC Screening and Q&A, Kardashian said watching the situation unfold on the show was "helping her heal".
"It's not easy, but it's also, I think, a form of therapy for me at the same time, and I like to see how the rest of my family responds to things.
"Those little things mean a lot to me, and I like to see that stuff, just how the whole family - not about this situation, but any situation - how we all rally around one another in times that are hard for us."