The night before she cradled her baby bump on Snapchat.
After a day of working out, Khloe showed up to the bash in a shimmering silver dress with her blonde locks pulled up and huge diamond earrings, preening for selfies and Snapchat clips, cradling her baby bump in one of the shots.
The source continued, "The whole family is especially happy for Khloe's pregnancy, and thinks that this is going to be her best year yet".
Aguilera also brought her daughter, Summer Rain Rutler, to the party, posing for a mother-daughter photo with Kardashian and her daughter, North West.
In the picture, the star looks cosy in a bright red knitted jumper that matched her lipstick as she stared out into the distance.
Long hair don't care Sporting long tresses that contrasted with her previous bob and bangs Jenner pouted for the camera alongside her half-sister
Khloe meanwhile lamented not drinking due to her pregnancy.
The insider added: "She has expressed some concerns about giving [birth] and the recovery, but she isn't freaking out".
Since then her followers have become adamant she is having a "baby girl" after the reality star appeared to post cryptic clues online. "Kylie is only trusting her closest friends and her sisters right now". She is expected to give birth earlier than Kardashian.