See what WTA stars have returned to successful careers after maternity leave. (AP Photo)

World No. 6 Victoria Azarenka announced on Twitter that she is expected a baby with her boyfriend by the end of the year.

"We couldn't be happier and feel very blessed to begin this exciting journey of building a family together," she writes.

The 25-year-old hasn't played since suffering a knee injury at Roland Garros. Her 2016 campaign was off to a promising start, having won both Indian Wells and Miami.

"I have been truly inspired by so many strong female athletes who return to the very top of their sport after having children, and I plan to do exactly that," Azarenka writes.

The protected ranking rules by the WTA for pregnancy state that:

"Maternity and injury/illness Special Ranking requests will be governed by the same rules. However, in case of absences due to maternity leave, for a player to be eligible for a Special Ranking, such player must be ready to play her first tournament within 12 months of the birth of her child."

A few players have become mothers and returned to successful careers, including Kateryna Bondarenko, Tatjana Maria, Evgeniya Rodina and Kim Clijsters.

Bondarenko retired before giving birth to her daughter, but came back in 2014. Her ranking is back up to No. 58 after a career-high of No. 29 in 2009.

Rodina was ranked No. 131 when she took a break in 2012. She gave birth to her daughter Anna in November of that year, and returned to the tour in 2013. The Russian is now No. 102.

Maria gave birth to daughter Charlotte in December 2013. Before going on maternity leave, she was just outside the Top 100, and now she's at No. 113.

Clijsters became the first mother to win a major when she won the U.S. Open in 2010, just two years after giving birth to her first daughter, Jada Elle.

The Belgian went on to return to No. 1, and is now expecting her third child.