ET: Khloe Kardashian gives birth to first baby with Tristan Thompson

Khloe Kardashian has welcomed her baby girl!

The "Keeping Up With the Kardashians" star gave birth to her daughter with NBA player Tristan Thompson on Thursday in a hospital outside of Cleveland, Ohio, ET can confirm. 

"Baby and mom are healthy," a source close to the Kardashians tells ET, adding that the little one is "beautiful" and does not yet have a name. 

Khloe's sisters Kim and Kourtney, mom Kris Jenner and best friend Malika Haqq were with her in the delivery room.

The days leading up to the birth were a turbulent time for the couple, who welcomed their first child amid reports that Tristan allegedly cheated on Khloe with multiple women.

A source told ET on Wednesday that Khloe "is completely devastated" by the allegations, and that Khloe's mother, Kris Jenner, recently flew to Cleveland "to be with her and support her in whatever she needs."

On Tuesday, after the first infidelity allegations surfaced, a source told ET that Khloe's family were all "rallying around her" during the tumultuous time, and that they tried to make sure Khloe focused on "having a healthy experience."

The source said that the allegations came as a shock to the Kardashian family, who "really like Tristan and have welcomed him into their family."

In the days leading up to her due date, before the allegations surfaced, Khloe spent her time keeping a low profile, relaxing at the couple's home in Cleveland and taking to Instagram and Snapchat to document the final days of her pregnancy journey.

The 33-year-old reality star has not shied away from baring her glowing pregnancy bod, sharing numerous snapshots of her baby bump in romantic snapshots with Tristan. On April 9, Khloe posted a touching photo of her and her shirtless boyfriend sharing a sweet kiss, which she captioned, "We are ready whenever you are little mama."

We are ready whenever you are little mama 🦋

A post shared by Khloé (@khloekardashian) on

In March, she posted another photo, from what appeared to be the same shoot, showing the expectant mom leaning against Tristan while baring her bump in a set of lacy black underwear. 

Khloe captioned the photo simply, "Mommy and Daddy."

Mommy and Daddy 📸 @sashasamsonova

A post shared by Khloé (@khloekardashian) on

The new mom revealed earlier this year that she was planning on giving birth in Cleveland, where her NBA star boyfriend plays for the Cavaliers.

Sources told ET in March that Khloe spent the weeks ahead of her delivery just relaxing and hanging out with her man in Ohio, while Tristan "has been hands-on with helping Khloe through the pregnancy," and that he's "very excited to be having a baby girl."

In the days leading up to her newborn daughter's arrival, Khloe took her app to open up about how she just wanted to go into labor already.

"Day by day, it gets harder and I get more impatient -- and not to mention more uncomfortable," she wrote. "So, while we wait, I have to stay busy. I'm not the type to lay around all day and be lazy (when I do, I get a little crazy!). I've already finished the nursery, so I'm happy to have that checked off the list."

Khloe also wrote about how she and Tristan spend their time together in Cleveland, explaining how they "have a very similar routine every day," which includes binge-watching their favorite TV shows together.

"Tristan and I have also been watching 'Billions,'" she says. "It's such an incredible show -- we LOVE it! We just finished Season One. It's such a good show to binge-watch. We're really trying to enjoy ourselves, but we're SO ready to meet our baby girl."

ET spoke with Khloe's sister, Kim Kardashian, in early April, and the mother of three said her younger sister was "freaked out" as her due date approached.

"I'm, like, the real one with her [about] what goes down and how it's going to go down," Kim explained, adding, "You cannot tell her anything right now that's too sensitive because she's just so freaked out. So, I can't really get into the whole, like, nipples and breastfeeding thing... She's just going to have to figure that all out and slowly."

However, Kim said that she has the utmost confidence in her sister's abilities when it comes to motherhood.

"It'll be fine. She knows," Kim said. "She's seen all of us go through it. She's prepared."

Khloe has also gotten a lot of pregnancy advice from her mom. ET spoke with the Kardashian family matriarch over the weekend at the Daily Front Row's 4th annual Fashion Los Angeles Awards, days before she flew out to be with Khloe, where she opened up about how her daughter was holding up in the days ahead of giving birth.

"I think [she's ready], so we'll see. When you have your first baby, you're scared," Kris shared. "I give her so much advice [that] she's sick of me. We all give her advice because, you know, most of us have had a child or two in this family."

Reports that the Good American founder was pregnant first broke in September. However, the expectant mom refused to comment or confirm the reports until December, when she took to Instagram to share the news alongside a photo of her bare baby bump, cradled by her and Tristan's hands.

My greatest dream realized! We are having a baby! I had been waiting and wondering but God had a plan all along. He knew what He was doing. I simply had to trust in Him and be patient. I still at times can't believe that our love created life! Tristan, thank you for loving me the way that you do! Thank you for treating me like a Queen! Thank you for making me feel beautiful at all stages! Tristan, most of all, Thank you for making me a MOMMY!!! You have made this experience even more magical than I could have envisioned! I will never forget how wonderful you've been to me during this time! Thank you for making me so happy my love! Thank you to everyone for the love and positive vibes! I know we've been keeping this quiet but we wanted to enjoy this between our family and close friends as long as we could privately. To enjoy our first precious moments just us ❤️ Thank you all for understanding. I am so thankful, excited, nervous, eager, overjoyed and scared all in one! But it's the best bundle of feelings I've ever felt in my life! ❤️❤️❤️

A post shared by Khloé (@khloekardashian) on

"My greatest dream realized! We are having a baby! I had been waiting and wondering but God had a plan all along. He knew what He was doing. I simply had to trust in Him and be patient. I still at times can't believe that our love created life!" Khloe wrote.

"Thank you to everyone for the love and positive vibes! I know we've been keeping this quiet but we wanted to enjoy this between our family and close friends as long as we could privately," she added in the caption.

On March 4, as part of the "Keeping Up With the Kardashians" season 14 finale, Khloe first revealed that she was expecting a little girl. She also took to Twitter to address the news, and sweetly gave a shout-out to Kylie Jenner and Kim Kardashian West's newborn daughters, Stormi and Chicago.

"I am now so excited my daughter will have forever best friends with Chicago and Stormi!! God is great!!! Thank you Lord for our princess," Khloe shared.

Just weeks before her daughter's arrival, Khloe opened up to her fans on Twitter that she and Tristan still hadn't settled on a name.

"I have a few that I like, but nothing is picked. It's so hard," she replied to one follower who asked about the baby's possible moniker. 

In response to another Twitter follower who asked if she might stick with the "K" name tradition started by her mom, Kris Jenner, when naming all five of her daughters -- Kourtney, Kim, Khloe, Kendall and Kylie -- she said, "I think a T but a K is an option as well. That's as far as I know."

This is Khloe's first child with Tristan, who shares a 1-year-old son with ex-girlfriend Jordan Craig.

For more on Khloe's high-profile pregnancy journey, check out the video below.