Kourtney Kardashian's world was rocked when she found out she is pregnant with baby No. 4 — and In Touch can exclusively reveal it's because she is unsure who the father is!

While the eldest Kardashian, 37, started sleeping with her on-again boyfriend, Scott Disick, 33, back in September, she was also hooking up with boxer and model Younes Bendjima, 23, during their time apart.

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kourtney kardashian and scott disick getty images

"She said the sex was better than it's ever been," an insider reveals of Kourtney and Scott, adding that "they discussed trying for another baby."

When they took their children — Mason, 7, Penelope, 4, and Reign, 2, away to Mexico back in November, "they didn't use birth control."

In Touch previously reported that Kourt was spotted out with Younes during one of her fights with her baby daddy.

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Younes Bendjima.

“Kourtney has a thing for boy toys, and Younes is just her type. She’s been boasting to pals about his amazing six-pack, telling them she can’t keep her hands off his sexy body. Scott hit the roof when he heard she was hooking up with Younes,” says the insider.

After months of speculation, the reality stars confirmed they were back together earlier this month, however it wasn't long before "they were back to fighting nonstop."

"They wanted to parent together," the source continues.

The mother-of-three dumped Scott in July 2015 after nine years of dating, because he was photographed snuggling up to his ex-girlfriend and celebrity stylist Chloe Bartoli in Monte Carlo.

Baby No. 4, whose gender and due date have yet to be released, will join their three siblings and famous cousins, North West, 3, Saint West, 1, and baby Dream Kardashian.

That has to be enough for a spinoff one day!

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