Khloe Kardashian is Pregnant with Tristan Thompson's Baby

Another day, another Kardashian pregnancy -- but this time it's Khloe ... TMZ has learned.

Multiple sources tell us Khloe Kardashian is pregnant with her first child, and the baby daddy is her NBA star boyfriend, Tristan Thompson.

Our sources say Khloe is 3 months pregnant. We're told Khloe conceived naturally. So far, she doesn't know the sex of the baby.

This now makes for 3 expecting Kardashians. We broke the stories ... Kim and Kylie are also expecting, and their babies should be delivered around the same time in mid-January.

Khloe and Tristan have been dating for 1 year, almost to the day.

Good news usually comes in threes -- unless Kourtney wants to get in on this too.