Kardashian and Thompson began dating in September 2016, with the "Keeping Up With the Kardashians" star soon proclaiming that she thought Thompson was the man she wanted to spend the rest of her life with.
Khloe, Thompson and the entire Kardashian-Jenner family celebrated their new addition with a huge, pink-themed baby shower in April.
She eventually shared a photo of her baby bump on Instagram, saying it was her "greatest dream realised". The reality star delivered the baby at a hospital outside of Cleveland.
It's been a rocky week for Kardashian and Thompson, after reports emerged that he allegedly cheated on Kardashian. "I had been waiting and wondering but God had a plan all along".
Kardashian and Thompson have not commented on the videos.
Insiders told TMZ that Khloe went into labor on Monday morning, but in social media clips she appeared to still be at home that evening. Kim Kardashian and Kanye West welcomed their third child, daughter Chicago, via surrogate in January, while Kylie Jenner gave birth to her first kid - a daughter, Stormi, with Travis Scott - in February. Her reaction to having a daughter on the way?
This is the first child for Khloe, and the second for Canadian basketball player Tristan, 26, who shares a one-year-old son named Prince Oliver, with his ex-partner Jordan Craig.
"Her current feelings are focused on her baby, as all the rest of the stuff will start making sense in the next few weeks", our source added. She also wants the baby to take on both of her parents' "big booties", she joked.