Pecker is a key witness in the case against the former US president, who is accused of falsifying business records to cover up hush-money payment
The 23-time Grand Slam singles champion is shown in profile facing left and her pregnant stomach proudly displayed, a small waist chain the only item she wore in the image by famed photographer Annie Leibovitz.
Williams said in the story she learned she was pregnant just before the Australian Open, which the 35-year-old American won to set the Open Era record for Grand Slam singles titles and move one shy of Margaret Court's all-time mark.
Williams revealed in April she was pregnant and would not play again this year. In the story, she insists she will return to tennis in January, which would allow her to defend her Australian Open crown.
"I don't think my story is over yet," she told the magazine.
Williams and Ohanian, the 34-year-old co-founder of social media website Reddit, will be married this year after their child is born, according to the article. They announced their engagement last December after meeting in 2015 in Rome.
In telling how Williams discovered she was pregnant, the article said took a pregnancy test only after a friend's nagging, dismissing the idea as a joke and taking it while she was working on her hair and makeup for a sponsor appearance.
"I went back to finishing hair and makeup, was laughing, talking. I was getting the styling done. An hour and a half later, I went back to the bathroom and I totally forgot about it because it was impossible for me," Williams told the magazine.
"So I went back to get dressed and I went back in the bathroom and I was like, 'Oh yeah, that test.'"
Williams said she "did a double take and my heart dropped. Like literally it dropped."
"Oh my God. This can't be. I've got to play a tournament. How am I going to play the Australian Open? I had planned on winning Wimbledon this year."
Williams sent her friend to the store to buy five more pregnancy tests, each producing the same positive result.
She telephoned Ohanian to fly to Melbourne early and when he did, she handed him a bag with the six pregnancy tests, shocking him as well, according to the story.
Williams was examined by a doctor who assured her she could play the Australian Open without harm to the fetus. She didn't drop a set in capturing the title.
"It just doesn't seem real. I don't know why. Am I having a baby?" Williams told the magazine last month.
"If you would have told me last year in October or November that I would have a baby, not be pregnant but have a baby, I would have thought you were the biggest liar in the world.
"This is kind of how I am right now. This is happening sooner than later and it's going by so fast."
She plans on preparations for the baby in the next few weeks, when moving will be more difficult and she will be "bored to tears."
"I don't know what to do with a baby," she said. "I have nothing.... I've done absolutely nothing for the baby room."
Pecker is a key witness in the case against the former US president, who is accused of falsifying business records to cover up hush-money payment
The oil and gas conglomerate and Fifa, the world governing body, sign major sponsorship agreement
Toomaj Salehi risks being hanged after the conviction on the Shariah charge of "corruption on Earth" by a Revolutionary Court
Aid groups warn any invasion would add to already-catastrophic conditions for Gaza's 2.4 million people
The American they will face Australia and Serbia on July 15 and July 17 as part of their preparation for the Paris Olympic Games
The leaders emphasise that the deal to release the hostages would bring an immediate and prolonged ceasefire in Gaza
Dubai-based Sumit Augustine has had a philosophical approach towards spending
The regional upswing also defies oil production cutbacks