Kelly Rowland and former Destiny's Child bandmate Beyonce Knowles Carter have been more like sisters than friends since childhood. And according to People, when Rowland talked about her biggest mistake, it centered around Queen Bey.

It was in 2011, when Beyoncé was pregnant with her first child, a baby who became the dance phenomenon Blue Ivy Carter. On the latest episode of the "Yeah, I F-ed That Up" podcast, Rowland recalled his biggest mistake, the moment he accidentally revealed the gender of Beyoncé and Jay-Z's first child on "Bang Showbiz."

"Oh my god. When Beyonce was pregnant with Blue, I mistakenly said the sex of [Beyonce's] baby." At the time, it slipped out that Jay Z said, "I'm going to buy that little girl everything possible."

"It was the worst moment ever. Because it wasn't anyone's business."

"It was a terrible moment. It wasn't my news, so I felt terrible. It honestly sucked. It's not my news, and I didn't mean to."

Beyoncé eventually welcomed Blue in January 2012 and twins Sir and Rumi in June 2017.

And speaking of Beyoncé and gender revelations, in a viral moment on the singer's Renaissance World Tour, she revealed the gender of a concertgoer's baby. During a performance in Cologne, Germany, Beyoncé paused the show to acknowledge a fan sign asking for her help: from the beginning of the show, she had seen this sign that read, "Reveal my gender. 'I want to do it right! Can someone hand me an envelope? She smiled wryly as she opened the letter with her gender on it.

"The Grammy winner simply said 'girl' into the microphone in a tone similar to her 2011 hit single 'Run the World (Girls),'" People reported." She then congratulated the soon-to-be parents amid cheers from the crowd."

"The crowd cheered for her, and she was the first to congratulate them.

"Congratulations!" Bey said.

"Congrats! God bless you!"