Serena Williams has been slammed on social media for saying she can't wait to give birth and become a "real woman."

"I have so much respect for so many women (for giving birth)," Williams said. "I am about to be a real woman now, you know? It's going to be something incredibly impressive to go through."

The 35-year-old tennis ace — who is due to give birth to her first child with fiance Alexis Ohanian, a co-founder of Reddit, in September — was lauded for winning the 2017 Australian Open one week after finding out she was pregnant.

But this week she faced ire from fans for the comments she made to the Daily Telegraph, an Australian newspaper, on Sunday.

Many took to social media to criticize the remarks for being retrogressive and insensitive to women who cannot or choose not to give birth.

In the same interview, however, Williams said she was "definitely" a feminist.

"I like to stick up for women and women's rights," the holder of a record 23 Grand Slam singles titles said. "So many things happen and I just think, ‘Wow, why don't we have a chance?' If that makes me a feminist, I am proud to be one."

Williams also confessed she was apprehensive about becoming a mother.

"There are barriers I hope to break so my baby, whether boy or girl, won't have to live under those stipulations," she said. "I always want to be the best at what I (do), so I am a little nervous."