Serena Williams reclaimed her No. 1 ranking on Monday, marking her 317th week atop the WTA rankings.
Williams passed Angelique Kerber for No. 1 despite not playing a match since late January, when she took home her seventh Australian Open title.
The 23-time Grand Slam winner posted a message for her unborn baby on Instagram, sharing her thrill of recapturing the No. 1 spot.
"I can't wait for you to join the players box next year," Williams wrote. "But most importantly, I am so happy to share being number one in the world with you."
Williams plans to miss the remainder of the 2017 season after confirming her pregnancy last week.