Khloé Kardashian is reportedly expecting her first child with boyfriend Tristan Thompson.

Khloe Kardashian

Khloe Kardashian

The 32-year-old 'Keeping Up With the Kardashians' star is allegedly pregnant with the 25-year-old Cleveland Cavaliers professional basketball player's baby, and although the news came as a "surprise" to the reality TV star, she is "so happy" she will be a mother.

Speaking to X17 Online, which has since been reported on the Mirror Online, a source said: "[Khloé's] so happy.

"The pregnancy came as a surprise, particularly since Tristan's ex-girlfriend is currently pregnant, but Khloé got on board with the idea of having a baby pretty quickly."

And the couple, who first appeared to go public with their relationship in September this year, are reportedly set to tie the knot prior to the birth, because the former 'Kocktails with Khloé' host and her 60-year-old momager, Kris Jenner, want "everything done correctly", so the pregnancy doesn't look like an "accident".

The source explained: "Khloé and Kris want everything done correctly. They don't want this to look like an accident and Khloé really wants to show the world that Tristan is her man. She wants to kind of follow tradition and have Tristan ask her mum for permission to propose, in hopes of making the engagement look more traditional and formal."

It has been reported Tristan has already asked Kris' permission to marry her daughter, but Kris has already opened up about Khloé's new beau and has admitted he is a "really nice guy".

Speaking previously about their relationship, Kris said: "They're really cute. You know, she's having a good time, he seems like a really nice guy."

Meanwhile Tristan's former flame, Jordan Craig, is due to give birth to her baby soon, and has recently shared a picture of her burgeoning bump at her baby shower last month.

Alongside the post, she wrote: "Although watching and feeling you grow everyday has made my pregnancy such an unforgettable, magical experience ... words cannot express how anxious and excited I am to finally meet you! (sic)."