Serena Williams
Serena Williams, photographed during the Met Gala in New York City, on May 1, 2017, isn’t announcing the gender of her unborn child. Getty Images

Mum’s the word for mom-to-be Serena Williams. The pregnant tennis star has no plans to announce the gender of her and fiancé Alexis Ohanian’s baby until the child’s birth.

She explained her decision in a post on Instagram early Thursday morning. Williams, 35, also took a moment to clarify a recent comment from twin sister Venus Williams, who referred to her unborn niece or nephew as “she.” Serena explained that she’s been jokingly calling her unborn by her sister’s names to butter them up.

The near slip of the tongue by Venus was made during interviews after a second-round victory at the French Open. Venus was asked what she hoped sister Serena’s baby would call her when the child starts talking. She joked that the baby, whom she referred to using female pronouns, would have a special title for her.

Read: Serena Williams Hits The Beach After Confirming Pregnancy

“She’s going to call me ‘favorite aunt,’” she told reporters (via ESPN).

While Serena’s being careful not to spoil the surprise of what she’s having, she wasn’t so cautious in announcing her pregnancy. During an interview with Entertainment Tonight, she revealed that she didn’t intend to go public about her pregnancy in that now-infamous Snapchat post. She assured the publication that it was completely accidental, which is why she deleted it shortly after.

“It was an accident,” she said. “I was on vacation just taking some time for myself and I have this thing where I’ve been checking my status and taking pictures every week to see how far along I’m going.”

At the time, even those nearest and dearest to Serena weren’t aware she was expecting. After the photo was posted and screen grabbed by fans, a rep for the tennis pro confirmed the exciting news. In a statement, her rep said that Serena would be sidelined for the rest of the 2017 tennis season and would return in 2018.

Fans were over the moon about Serena’s baby news, but there were no shortage of haters. Ilie Nastase, a former high ranking tennis player, made a particularly ugly comment about Serena’s pregnancy that caught her attention. BBC reported that the 70-year-old speculated about whether or not Serena and her fiancé’s child would look like “chocolate with milk,” which prompted a swift response from Serena on Instagram.

Read: Fans Are Elated About Serena Williams’ Pregnancy Announcement

She shared a lengthy post, bashing Nastase for making “such racist comments” about her unborn child. Serena went on to say that society has a long way to go before we achieve true equality. She vowed to continue to exude “love, light and positivity” in the hopes of drowning out all the ugliness in the world.

Despite the controversy, Serena and her beau are elated about becoming parents. The pregnant athlete shared an especially heartwarming post about her child on Ohanian’s birthday, writing that her pregnancy has shown her a strength she never knew she had. She added that she was so looking forward to her son or daughter sitting with Ohanian in the player’s box at tennis matches in the years to come.

The photo marked the first time Serena showed off her growing baby bump since accidentally revealing that she’s pregnant. At the time, she was about 20 weeks along.