Khloé and Kylie "are approximately 4 months along," the source tells PEOPLE

By Melody Chiu and Karen Mizoguchi
September 26, 2017 07:20 PM

For Khloé Kardashian, 33, and Kylie Jenner, 20, the pregnancy journey will be one taken together — and they could not be happier about it.

“Kylie is over the moon about her pregnancy. Khloé and Kylie are both due around the same time. They are approximately four months along,” a source tells PEOPLE.

“Kylie loves how close-knit her family is and is thrilled to bring that to her own family. She feels more prepared than ever, especially since she will be sharing this journey with Khloé,” the insider continues, adding, “They are looking at it like a unifying experience for them as sisters.”

Multiple sources confirmed to PEOPLE on Tuesday that the Keeping Up with the Kardashians star and her NBA boyfriend — whom she has dated since September 2016 — are expecting their first child.

“Yes, Khloé and Tristan are expecting and they are absolutely thrilled,” a separate source told PEOPLE. “This isn’t something they were in a rush to announce to the whole world, and it’s only been in just the past week or so that they’ve felt comfortable telling most of their inner circle. Things were complicated a bit by Kylie’s announcement as they don’t want to be seen as intruding on that moment for her but it is now reaching a point where Khloé doesn’t want to be openly lying to people, and just staying quiet isn’t going to work anymore.”

The baby will be the first child for Khloé. Thompson, 26, welcomed a son named Prince Oliver with his ex-girlfriend Jordan Craig in December 2016.

Credit: Kevin Mazur/WireImage

Want all the latest pregnancy and birth announcements, plus celebrity mom blogs? Click here to get those and more in the PEOPLE Babies newsletter.

Khloé’s pregnancy comes days after sources confirmed to PEOPLE on Friday that Kylie is expecting a baby girl with her boyfriend Travis Scott.

“Getting pregnant at the same time was totally unplanned but they are really happy about it,” the source says. “Kris is trying to be supportive of Kylie even though she’s worried. But she particularly loves Travis and the entire family has known him for a very long time so they are more comfortable with the situation.”

And there will be one more baby joining the Kardashian-Jenner family.

Kim Kardashian West and husband Kanye West are expecting their third child after hiring a surrogate to help them expand their family. The couple is already parents to 4-year-old daughter North West and 21-month-old son Saint West.

“This is something Khloé has wanted for years and years and yet it’s more than that: she didn’t want it unless she was in the right relationship for it. She never let it happen with Lamar, intentionally, and she never considered it with James or French or anyone else she has seen,” a source previously told PEOPLE about Khloé’s marriage to Lamar Odom and her past romances with James Harden and French Montana.

“This is such a wonderful moment for her: not only is she going to be a mother, she is going to be raising a child with a man she truly loves. Everyone is over the moon for them both.”