The tennis ace confirmed Wednesday she is 20 weeks along in her pregnancy, showing off her growing baby bump in a bright yellow bathing suit on Snapchat.
Williams, 35, is engaged to Reddit co-founder Alexis Ohanian, 33. The couple shared a post-Easter snap from the beach on Tuesday.
Williams competed in the Australian Open this year, defeating sister Venus Williams to win her seventh title in the tournament.
Reps for Williams did not immediately return a request for comment.