Williams' husband, Alexis Ohanian, also shared a heartfelt message to his baby girl on her special day. "How has it already been two years? Happy cake day @olympiaohanian ?♥️ Thank you for being the greatest thing we've ever done," he captioned a photo of the family of three's adorable hands.
He went on to advocate for paid paternity leave, a cause that has been near and dear to his heart.
"And thank you for teaching me that every parent in the US deserves those first months with their newborn," he continued. "I'm a better business leader because of it. #PaidFamilyLeave."
Last month, the 36-year-old co-founder of Initialized Capital and Reddit opened up in a personal essay for NYT Parenting about his decision to take 16 weeks of leave when he and Williams welcomed their daughter in September 2017.
“Nothing could have dragged me away from my wife and daughter in those hours, days and weeks -- and I’m grateful that I was never forced to choose between my family and my job,” he wrote.
“Serena spent days in recovery fighting for her life against pulmonary embolisms. When we came home with our baby girl, Serena had a hole in her abdomen that needed bandage changes daily,” he recalled of his wife, who had an emergency C-section. “She was on medication. She couldn’t walk.”
“Spending a big chunk of time with Olympia when she was a newborn gave me confidence that I could figure this whole parenting thing out,” he added. “As an only child with no cousins, I didn’t grow up around babies; in fact, I had never held one until my daughter was born. At first, holding her terrified me. I am a giant and she’s so tiny… What if I break her? I didn’t -- which was encouraging -- and then I learned how to calm her crying, rock her to sleep and handle her toddler years with grace.”
Along with their daughter's birthday, Sunday also marks the day Williams will compete in this year’s U.S. Open tournament against Croatian tennis pro Petra Martić.
"I actually prefer playing in the day because I get to go home and see my baby," Williams said during an on-court interview on Friday. "I’ve been missing her the last few nights when I play."
"It's different," she continued about being apart from her daughter to work. "In the beginning she would really be upset when I left. And now she's a little bit better. I think I'm a little more upset. But at the same time, she definitely still takes it a little hard. She's still super young."
She added that her heart "literally aches" when she has to leave.
"You know, it's hard. Sometimes my heart literally aches when I'm not around her. But, you know, it's good for me, I guess, to keep working and just to all moms out there that it's not easy. It's really kind of painful sometimes. Sometimes you just have to do what you have to do," Williams shared.
"Usually I'm with her, I can train really early in the morning and be done pretty early with my day, and I can just stay with her for the rest of the day," she added. "In tournament schedule, it's totally different, so I'm kind of pushed out of my usual day-to-day life. Oh, my God, I'm not with her. That's been the most, I mean, 'the' toughest thing I have ever dealt with in my career."
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