Here’s episode description for 90210 Season 1 finale. Episode airs on May 19.
Adrianna and Navid are forced to make an impromptu exit from the prom when Adrianna goes into labor. Dixon confronts Ethan about Silver when he notices that Ethan might be developing feelings for his girlfriend. Meanwhile, Annie reaches her tipping point when Naomi accuses her of trying to hook up with Liam and some of her peers – still angry about the after party fiasco – decide to take both verbal and physical action against her.
( source: 90210 spoilers via CW ) edit: also posted on TV.com