She has a valid reason, though.

Serena Williams won't be celebrating her daughter Olympia's first birthday due to her religious beliefs, the tennis great revealed during a press conference.

"Olympia doesn't celebrate birthdays. We're Jehovah's Witnesses, we don't do that," she said.

The faith doesn't observe any holidays that have a pagan origin, including Christmas and Easter. The athlete has talked openly about her religion over the years, so this doesn't come as a complete surprise.

"I am Jehovah's Witness. I think if you don't believe in God, it's going to be tough to live life because pretty much that's the basis of life, it comes from God. Being a Jehovah's Witness, obviously we believe in God and the Bible. And without Him, I wouldn't be here right now. I really thank Him for everything," she previously told ASAP Sports.

Hold the presents, people!