Former world number one Naomi Osaka has announced that she is pregnant and will be taking a break from tennis until 2024.

"I know that I have so much to look forward to in the future, one thing I'm looking forward to is for my kid to watch my matches and tell someone, 'That's my mom' haha," she wrote on Twitter, accompanied by a picture of a pregnancy scan.

"2023 will be a year full of lessons for me, and I hope I'll see you guys at the start of the next one cause I will be back at the Australian Open 2024. Love you all infinitely," she added.

The 25-year-old Osaka has not played a tennis match since September and her withdrawal from the Australian Open, which starts next week, had puzzled many observers.

Osaka had not explained her absence until Wednesday.

Her last tournament appearance was at the Pan Pacific Open in Tokyo in September, where the home favourite withdrew before her second-round match, complaining of abdominal pain.

The top ranked player in the world in 2019, the Japanese player, who grew up in the United States, is now ranked 47th in the world.

Osaka has won four Grand Slam singles titles with triumphs in the Australian Open in 2019 and 2021 and the US Open in 2018 and 2020.

She was named the world's top-earning female athlete for 2022 by Forbes, with reported earnings of $51.1 million.

Her commercial success was not reflected on the court last year however as she suffered first-round defeats at both the French and US Opens and withdrew from Wimbledon with an Achilles injury.

"These few months away from the sport have really given me a new love and appreciation for the game I've dedicated my life to. I realize that life is so short, and I don't take any moments for granted; every day is a new blessing and adventure," she wrote in her statement on Wednesday.