Kylie Jenner Suspected That Kourtney Kardashian Was Pregnant 2 Months Before She Made Her Announcement

The Kylie Cosmetics founder noticed something was up with her eldest sister in April

Kylie Jenner is keeping an eye on her sisters at all times.

In Thursday’s episode of The Kardashians, viewers saw the Kylie Cosmetics founder, 26, jokingly ask her eldest sister Kourtney Kardashian Barker if she was pregnant during filming.

At their niece True Thompson’s fifth birthday party — daughter to Khloé Kardashian and Tristan Thompson — Kourtney, 44, greeted her youngest sister by proclaiming, “I’m like so exhausted, I can’t even stand up.”

After Kylie said "I love you," she asked Kourtney, “Are you pregnant?” Kourtney immediately denied she was.

Despite her denial, Kourtney was in her first trimester when the scene was filmed in April. Kylie caught onto her sister’s change in behavior, but it was not until June that Kourtney announced her pregnancy.

Related: Kourtney Kardashian Celebrates Sister Kim's Birthday with Joke About Their Feuds: 'The Joys of Sisterhood'

During the party, their mother, Kris Jenner, proposed Kourtney have some of the birthday cake. However, she declined and listed out the foods she’d cut out of her diet.

“No sugar… so I can’t have either of those,” Kourtney said. “I don’t drink coffee. I’m caffeine-free right now, soy-free, sugar-free, gluten-free, alcohol-free.”

Kourtney's husband, Travis Barker, joked with the two that his wife is currently “free of everything.”

Kourtney publicly announced that she was pregnant with her fourth child during a Blink-182 concert in June. A video showed her jumping up and down in the crowd while holding up a handwritten sign with large black letters that read, “Travis I’m Pregnant!”

The sweet video continued with Barker, 47, looking shocked on stage as one of his Blink-182 bandmates is heard saying, "Someone's having a baby!" The surprised drummer then made his way into the audience to embrace his wife.

Related: Kylie Jenner Spends Festive Fall Outing at a Pumpkin Patch with Kids Stormi and Aire — See the Photos!

The Kardashians star later revealed in September that she underwent “emergency fetal surgery” to save their baby’s life.

Kourtney, who shares son Mason, 13, daughter Penelope, 11, and son Reign, 8, with ex Scott Disick, said the emergency operation “opened [her] eyes to a whole new world of pregnancy that [she] didn't know about in the past."

After documenting her in-vitro fertilization (IVF) journey on the Hulu series, Kourtney told Vogue that she and Barker “just got pregnant naturally.”

"It was an indescribable feeling," she added. "Shock, then super-happy, fear sets in, worry, but I remembered then to have gratitude."

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New episodes of The Kardashians drop every Thursday at 12 a.m. ET on Hulu.

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