The pair have been dating for just five months but are already expecting their first child together, although the couple are not said to be considering marriage anytime soon because they haven't been together long enough.
Sources connected to the 20-year-old reality TV star and the 25-year-old rapper told gossip website TMZ that they're not planning to tie the knot in the near future, with one saying: ''They're still trying to figure out their relationship.''
While the pair are not thought to be discussing marriage, they have been speaking about raising their impending child.
Kylie is said to have been keen to have a baby, and fell pregnant around a month after hooking up with the 'Butterfly Effect' hitmaker.
Caitlyn Jenner is said to have mixed feelings about her daughter's pregnancy, but will support the 'Keeping Up With the Kardashians' star.
A source recently said: ''Caitlyn is excited for Kylie but is also worried and thinks she is too young to move forward with such a big life decision like this.
''Caitlyn is supportive of her daughter, of course, but she doesn't necessarily think this is the right time for Kylie.
''She has a hugely successful business and Caitlyn doesn't want to see that taken away from her.''
Kylie is said to be delighted with the support of her family.
A source said: ''The family is over the moon! Kylie loves how close knit her family is and is thrilled to bring that to her immediate family. Kylie feels more prepared than ever to be a mom.''
What's more, Kylie could see a familiar face in her antenatal classes because her half-sister Khloe Kardashian is also thought to be expecting her first child with her boyfriend Tristan Thompson.
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