EXCLUSIVE: Serena Williams Lives for Pal Kelly Rowland's Pregnancy Book: 'I Study It. I Highlight Things in It

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Serena Williams is getting through her pregnancy with a little help from her friends.

Williams, 35, is expecting her first child with fiance Alexis Ohanian, and on Wednesday revealed that she's turned her friend Kelly Rowland's book, Whoa Baby! A Guide for New Moms Who Feel Overwhelmed and Freaked Out (and Wonder What the #*$& Just Happened), into her own personal study guide.

"It's just raw," Williams said, as part of an interview on behalf of her sponsor, Tempur-Pedic. "It's everything that no one wants to tell you. I highlight things in it. I study it. It's been really, really, good for me." 

In an exclusive interview with ET about the book in April,  Rowland said that all moms "love hard...it doesn't matter if you're a celebrity mom or a mom that is a stay-at-home mom...we're all in this together."

WATCH: Serena Williams' Fiance Alexis Ohanian Says She'll Be An 'Awesome Mom'

Earlier this year, Williams debuted a series of advertisements for Tempur-Pedic, and says now that she's pregnant, she truly appreciates the power of sleep. "Sleep, I hear, has been really awful for a lot of people, but for me it's been amazing," she says. "I watch tutorials of how [pregnant women] have to set up the pillows, and I'm like, 'Wow, I don't have to do that at all.'"

MORE: Why Serena Williams Is the Greatest Athlete of All Time

Another star of the advertisements -- and Williams' Instagram -- is her stuffed monkey, Max. "Max was so excited to be in the commercial," she laughs. "He was ready. He was smiling the whole time."

So is Williams going to pass Max down when the baby arrives? "I've thought about that, and I think I'm going to keep him," she says. "But maybe, one day, if I ever grow up, I'll pass Max onto the baby." 

To see Williams and her bump practicing on the court, watch the video below:

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