Khloe shouted out Kylie Sunday with a throwback photo featuring the both of them showing off their baby bumps ... and it's clear Kylie had a decent head start.
The still-expecting mom captioned the pic with a heartfelt message ... "Congratulations My Sweet Kylie! ... 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."