Under a photo of the model basking in the sun on a Miami balcony in a cropped top showing her slight baby bump, Kardashian wrote "My beautiful babies in Miami."
The smitten reality television star followed the caption with a line of emojis including a bride, baby, and heart-eye faces.
The post comes soon after Kardashian described expecting with his wife-to-be as "exciting."
"I mean, it's my first time, so everything is exciting, literally," the star told E! News of his impending parenthood. "I'm happy and I just like to keep it, you know, keep it private. As private as can be."
Kardashian and Chyna were first linked in January and became engaged in April. The couple announced they're expecting their first child May 6, but reportedly intended to reveal the news on Mother's Day, May 8.