The 38-year-old actress recalled on Thursday's episode of Watch What Happens Live how Spears unintentionally leaked that Saldana was expecting twins with husband Marco Perego.
"It's so true," Saldana told host Andy Cohen. "It's really true, but literally, the way that it happened was so innocent that I never even thought of holding her accountable to anything."
"We were on the same flight from LA to New York and we just talked for the duration of the flight. She has two boys. I was having twins. We had such a beautiful talk -- and I forgot. It never even occurred to me to tell her not to say anything," she recounted.
"We weren't trying to hide it; we were just trying to be discreet," the star explained. "And then when she disclosed it, she was just being Britney. I don't mean that in a negative way. I mean that in the way that she lives her life in such truth."
Saldana, who shares 2-year-old twins Cy and Bowie and 2-month-old Zen with Perego, said she hasn't seen Spears since the flight. Spears, who co-starred with Saldana in the 2002 movie Crossroads, spilled the pregnancy news while discussing the possibility of another film with Saldana.
"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," the singer told Entertainment Tonight in September 2014.
Spears herself is mom to 11-year-old Preston and 10-year-old Jayden with ex-husband Kevin Federline. She is dating Sam Asghari, and shared a video of herself and the model frolicking in a pool last week.