Snooki & J-Woww: Jersey War!

Gym, tan, catfight! As Nicole "Snooki" Polizzi and Jenni "J-Woww" Farley begin filming their Jersey Shore spinoff, Star has learned, the former BFFs are feuding furiously over Snooki's surprise pregnancy.

Despite her denials, Snooki, 24, is pregnant by her boyfriend, Jionni LaValle, as Star reported more than a month ago. And it has thrown a wrench into the plans for her upcoming MTV series with her former bestie.

"They are having to redo the creative direction of the spinoff because of the pregnancy," an insider explains.

Instead of following the girls as they party their way through New Jersey, sources say, the show will focus on Snooki as she prepares to welcome her own little meatball — and J-Woww, 26, isn't happy about it.

"Jenni thought the show was supposed to be about their friendship, and now Snooki is causing so much drama because of the baby," an insider tells Star. "She's fed up with Snooki getting all the attention."

And sources say she's making her feelings known on set. "They're just fighting all the time," one source tells Star. "When they're on camera, they act like nothing is wrong — but there's so much animosity between them when the camera's down. It's uncomfortable for everyone."