The 'Keeping Up With the Kardashians' star - who is expecting her first child with boyfriend Tristan Thompson - shared an intimate photo of herself posing with her younger sibling, with both their bumps exposed, as she congratulated the 20-year-old beauty on the birth of her and Travis' Scott's daughter.
Khloe shared the picture after Kylie not only finally confirmed rumours she'd been carrying her first child, but revealed her little girl was born on 1 February.
She captioned the image: ''Congratulations My Sweet Kylie! What a magical ride it's been! I'll miss you bumping along with me. Never in a million years did I think we would do this together but it's been that much more special because of it.''
And the 33-year-old star revealed she and Kylie had given one another new nicknames during their pregnancies.
She added: ''God is so great!! He had His plan all along! I love you little mama [hearts] love big mama (sic)''
Meanwhile, Kylie's best friend, Jordyn Woods, has praised her pal's ''growth and maturity''.
She shared a photo taken at Kylie's baby shower and wrote on Instagram: ''Your growth and maturity over this time never failed to amaze me. So excited for this new addition! Wifey 4L (sic).''
Kylie took to Instagram on Sunday (04.02.18) to announce she had welcomed a daughter into the world on Thursday (01.02.18).
She shared in the accompanying post: ''I'm sorry for keeping you in the dark through all the assumptions. I understand you're used to me bringing you along on all my journeys. My pregnancy was one I chose not to do in front of the world.
''I knew for myself I needed to prepare for this role of a lifetime in the most positive, stress free and health way I knew how.
''There was no gotcha moment, no big paid reveal I had planned.
''I knew my baby would feel every stress and every emotion so I chose to do it this way for my little life and our happiness.
''Pregnancy has been the most beautiful, empowering and life changing experience I've had in my entire life and I'm actually going to miss it.
''I appreciate my friends and especially my family for helping me make this special moment as private as we could. My beautiful and healthy baby girl arrived February 1st and I just couldn't wait to share this blessing.
''I've never felt love and happiness like this I could burst. Thank you for understanding.''
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