Now, she's making history as a fully-formed human baby on the cover of Vogue.
She had an emergency C-section after her heart rate dropped dangerously low.
The day after the operation, she fell ill and doctors found several small clots in her lungs.
She was immediately given a drip, but when constant coughing from her pulmonary embolism opened up the scar from the c-section, her abdomen quickly filled with her now-thinned blood from the same drugs which were saving her life.
After the ordeal, Williams was unable to get out of bed for six weeks.
Williams also told Vogue about her first few months of motherhood, confessing, "No one talks about the low moments-the pressure you feel, the incredible letdown every time you hear the baby cry". "I'm not sure why we think that way, but I know that we're sometimes taught to not dream as big as men, not to believe we can be a president or a CEO, when in the same household, a male child is told he can be anything he wants".
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Williams, who married Reddit co-founder Alexis Ohanian at a star-studded wedding in New Orleans in November, said being a mother may boost her quest. The emotions are insane'.
But that's not to be confused with the idea that Serena is anxious about reclaiming her spot as number one when she returns.
And she's so in love with baby Alexis she's even thought about hanging up her tennis racquet.
She will be defending her Australian Open title in March at Indian Wells, and will also debut a new clothing line in March on her website. "I'm well aware of the record books, unfortunately".
However, in an interview with Vogue, the former world No 1 said that her hiatus had in no way diminished her drive and she will definitely be targeting a return to the top of the rankings once she is back. "But not yet. Maybe this goes without saying, but it needs to be said in a powerful way: I absolutely want more Grand Slams".
Williams, a 23-time Grand Slam singles champion, gave birth to Alexis Olympia in September. "But if there is a clear number one, that's cool, too, because it's like, yeah, I'm gonna come for you", she added. It will be cool to see if I get there again, to what I call my spot - where I feel I belong. I don't play to be the second best or the third best.