SERENA BARES HERS BABY SHOCK & MORE

I thought pregnancy test was ‘a joke’

A pregnant Serena Williams bared her baby bump in a stunning pose for the cover of the August issue of Vanity Fair — in which she revealed she didn’t believe she was even having a baby at first.

She told the magazine (inset) that, despite starting to vomit and getting enlarged breasts, she resisted taking a pregnancy test until a good friend insisted in January.

“I’ll take it just because (a) to prove you wrong and (b) because it’s fun, whatever,” Williams, 35, told the magazine. “It’s like a joke. Why not?”

When the results came back positive, the joke turned to real- ity, she told the magazine. “My heart dropped. Like literally, it dropped,” she said.

“Oh, my God, this can’t be . . . How am I going to play the Australian Open?”

She then took five more tests, just to be sure. They all turned up positive.

To tell the news to her boyfriend, Reddit co-founder Alexis Ohanian — who would soon become her fiancé — she put all the test strips in a bag and handed them to him.

Despite her worries about the Australian Open, which was scheduled for just days after learning of her pregnancy, Williams played anyway — and she won.

It was the 23rd grand slam sin- gles title of her career.

The interview and nude photos by Annie Leibovitz come as Williams has been waging a war of words with retired tennis bad boy John McEnroe — whom she told to “respect my privacy” after he gave an interview in which he speculated she would only be “like 700 in the world” when ranked against men.