According to Ben Widdicombe of Avenue Magazine, the 37-year-old said that her older sister's alleged baby news was "not true" on Tuesday afternoon while on the set of a photo shoot for the luxury publication.
Hours prior, Page Six had published a report claiming that the 40-year-old billionaire was expecting her first child with her venture capitalist fiancé, Carter Reum, who is also 40.
But Paris herself denied the story, saying she received thousands of text messages and phone calls following the article's publication.
"Yes, I am pregnant with triplets, so thank you guys for the congratulations. I really appreciate it, and I'm just so excited for motherhood," she said Tuesday on her podcast, This Is Paris. "Actually, I'm just kidding. I am not pregnant. Not yet. I am waiting 'til after the wedding. My dress is being made right now, so I want to make sure it looks gorgeous and fits perfectly."
Paris and Carter have been candid about their wishes to start a family, with Hilton revealing in January of this year that she had been undergoing in vitro fertilization (IVF) treatments.
During IVF, mature eggs are surgically retrieved from a person's ovaries and fertilized by sperm in a lab. The subsequent embryo or embryos are then transferred to a uterus – whether it be the egg donor's or a surrogate's.
"He's just my dream guy. … [Carter is] 100 percent [the one]," Paris said on the Trend Reporter podcast at the time. "We talk about [planning a wedding] all the time and planning our babies' names and all of that."
Despite her denial, fans could have sworn Hilton was sporting a fuller figure when she was photographed out and about with Reum earlier this month.
Wearing a baby blue empire waist chiffon dress, the otherwise slender fragrance touter showed off what seemed to be a much bigger bosom, and her typically tiny waist appeared just slightly more pronounced.
Her reps never responded to Radar's request for comment.
As for the husband-to-be, Carter proposed in February with an emerald-cut diamond ring while he and his leading lady were vacationing together on a private island. Hilton announced the happy news days later on her milestone birthday.
"When you find your soulmate, you don't just know it. You feel it," she captioned a photo of the dreamy moment. "My love & I have been together since our first date, and for my birthday, he arranged a special trip to tropical paradise."
"As we walked to dinner along the beach, Carter led us to a cabana adorned with flowers and dropped to one knee," she went on. "I said yes, yes to forever. There's no one I'd rather spend forever with."
She added, "To see more photos of my birthday dream come true, visit ParisHilton.com. Here's to Love - the Forever Kind #Engaged #SheSaidYes."
Speaking to Vogue at the time, the Simple Life alum said she was "excited about this next chapter and having such a supportive partner. Our relationship is one of equals. We make each other better people. He was absolutely worth the wait!"