Kim Kardashian -- Sex Tape Sales Erupt After Baby News

Kim Kardashian's sex tape sales have exploded since Kanye West told the world they're expecting ... TMZ has learned.

We spoke to the folks at Vivid Entertaintment -- which owns 'Kim K. Superstar' -- and discovered lots of Kim's fans are celebrating the baby with umm ... visual aids.

Vivid says video-on-demand purchases of the sex tape have spiked 80% since Sunday night ... the fattest increase they've seen since Kim's wedding to Kris Humphries.

Further, Kanye's been boosting biz for months now. We're told overall sales of Kim's sex tape -- be it VOD, online, or DVD -- have steadily increased every month since he and Kim hooked up last Spring.

So, the real winner in the whole Kimye baby hysteria -- Ray J!