Serena Williams and Alexis Ohanian attend the Met Gala in May 2017. (Photo: Jackson Lee/FilmMagic)

She’s a mom! Tennis champ Serena Williams has welcomed her first child with her fiancé, Reddit cofounder Alexis Ohanian, a source close to the tennis pro confirms to Us Weekly.

Williams, 35, gave birth to a baby girl at a hospital in Palm Beach, Florida, on Friday, September 1, the source tells Us.

As previously reported, Williams accidentally announced her pregnancy in a Snapchat photo on April 19. She posted a selfie that showed off her tiny baby bump, writing that she was “20 weeks” pregnant.

“On social media you press the wrong button and…30 minutes later I missed 4 calls and I’m like, ‘That’s weird,'” she explained to Gayle King during a TED conference in Vancouver days later.

Famous Celebrity Pregnancies: Baby Bump Hall of Fame

Following the announcement, Williams shared several more baby bump pics on social media and opened up about becoming a mom. She graced the August 2017 cover of Vanity Fair, stripping down to just a thong.

“I don’t know what to do with a baby,” the she told Vanity Fair. “I have nothing … I’ve done absolutely nothing for the baby room.”

Celebrity Babies of 2017

The athlete learned that she was expecting shortly before winning the Australian Open in January. She was so shocked that she took six pregnancy tests.

Cutest Celebrity Baby Announcements

“[I] did a double take and my heart dropped,” she told Vanity Fair. “Like literally it dropped.”

Williams and Ohanian, 34, got engaged in December 2016. The pair have yet to announce a wedding date.

Want stories like these delivered straight to your inbox? Sign up now for the Us Weekly newsletter!

For the latest celebrity entertainment, news and lifestyle videos, subscribe to Us Weekly’s YouTube page!