Katy Perry announced her pregnancy to the world in the most public way possible, by unveiling her baby bump in a video for her song "Never Wore White."

But outside of her friends and family, she's now revealed that she shared her pregnancy secret with Harry Styles.

During a DJ set Tuesday on BBC Radio 1, Perry requested Styles' hit "Lights Up," and reminisced about the fact that she remembered him from when she was a guest judge on the U.K. version of "The X Factor" in 2010, when the group One Direction was first formed.

"I actually saw him on a plane before I announced that I was pregnant," she continued. "And we were having a conversation, and I was like, 'Yeah, I'm pregnant,' just, like, off the cuff, 'cause I was like, 'What else do you say?'"

"He was so happy for me. He actually ... .he was so sweet. I was crouching down by his seat on the plane and once I had told him that, he got up out of his seat and said, 'Here, sit in my seat!'" she laughed.

"And I was like, 'No! I'll just go sit in my own seat, which is right across the way.' But he's, like, a complete gentleman!"

Everyone else found out about Perry's pregnancy in March. In April, she announced that she and her fiance Orlando Bloom were having a girl. It's not clear exactly when Perry's due, but her other big delivery -- her new album -- is coming out August 14.