Kylie Jenner aware of Kourtney Kardashian's pregnancy before announcement

Kylie Jenner is constantly watching over her sisters.

Watchers witnessed the 26-year-old entrepreneur of Kylie Cosmetics lightheartedly inquire about her older sister Kourtney Kardashian Barker's pregnancy while taping Thursday's episode of The Kardashians.

Khloé Kardashian and Tristan Thompson's daughter True Thompson turned five years old, and Kourtney, 44, arrived at the celebration and told her youngest sister, "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.

Kourtney was in her first pregnancy when the sequence was taped in April, despite her denial. Although Kylie saw her sister's altered conduct, Kourtney didn't reveal her pregnancy until June.

Kris Jenner, their mother, suggested that Kourtney share some of the birthday cake during the celebration. She declined, though, and gave a list of the foods she would no longer eat.

“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.”

Travis Barker, Kourtney's spouse, made light of the situation by saying that his wife is presently "free of everything."

During a Blink-182 performance in June, Kourtney made her fourth child's pregnancy publicly known. In a video, she could be seen bouncing around the crowd and putting up a handwritten sign that said, "Travis I'm Pregnant!" in big black letters.