Go ahead and add another title to Serena Williams’ collection: Mom.

The tennis star announced via social media on Wednesday that she gave birth to a girl named Alexis Olympia Ohanian Jr.

Williams posted about her baby on Instagram and Twitter accounts and is heard saying in a video, “We had a lot of complications, but look what we’ve got.”

The 35-year-old Williams said in late December that she was engaged to Reddit co-founder Alexis Ohanian.

Williams wrote Wednesday that their daughter was born on Sept. 1 and weighed 6 pounds, 14 ounces. One posting also says about the newborn, “Grand Slam Titles: 1.”

Williams won her 23rd Grand Slam singles championship at the Australian Open in January — while she was pregnant.

She has not competed anywhere since but has said she intends to return to competition by next year’s Australian Open, which starts on Jan. 15, 4½ months after her baby was born.

“If she’s ready, she’ll play. If she’s not, she won’t play. I’m not a doctor. I can’t decide when she’s going to be ready to practice. If we can have enough practice so she can be ready, she’ll play,” Patrick Mouratoglou, Williams’ coach, said last weekend at the U.S. Open.

“I don’t want her to go compete if she’s not ready,” Mouratoglou said. “I told her: ‘You come if you’re ready.’ And I will do everything for her to be ready for Australia. But if she is not ready,…