Serena Williams gives birth to baby girl, welcomes first child with fiance Alexis Ohanian

US tennis super star Serena Williams was blessed with baby girl, the first child for the former world number one tennis player, her coach Patrick Mouratoglou said on Twitter on Friday.

The 35-year-old American, who is engaged to Reddit co-founder Alexis Ohanian, has not competed since winning the Australian Open in January but has posted several videos to social media showing her hitting balls during her pregnancy.

"Congratulations @SerenaWilliams for your baby girl. I am so happy for you and I feel your emotion," Mouratoglou wrote. "Btw ... I wish you a speedy recovery... we have a lot of work ahead of us," he added.