Saldana, 36, confirmed her pregnancy for the first time last month, reported E! Online.
Asked if she will be dressing up for the Halloween celebration, which takes place on October 31, she replied, "I might. I might need three costumes. I might have to make some adjustments, but it would be nice."
Zoe's admission came a few weeks after her friend and 'Crossroads' co-star Britney Spears accidentally let slip she is having twins.
When the singer was asked if she would like to film a sequel to her 2002 film with Zoe, Spears had said, "Who knows? That's a very good idea. But she's pregnant with twins right now. So I'm sure she's got a huge future ahead of her.