New York, New York - Cardi B shared a sweet tribute to her son in honor of his third birthday!

They grow up so fast! Cardi's little boy, Wave Offset Cephus, is already three, and the WAP rapper and her estranged hubby took to Instagram to share sweet messages for his birthday.

"I was soo happy when I found I was having a baby then all of a sudden I got so scared when I found out I was having a boy I'm such a girly girl," she recalled.

"You make it easy tho getting into that sporty mom bag."

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She concluded her sweet post saying, "My baby love his momma soo much. Ill always have your back, front and sides."

Offset also celebrated Wave, writing: "God Greatest Gift is a child…..My youngest turned 3 today happy bday Wave Set love you son son!"

Along with the sweet words, Cardi shared lots of pics from Wave's airplane-themed birthday bash over the weekend, as well as an adorable clip of her feeding him as a newborn.

Wave is also about to get another sibling, and judging by Cardi's latest pics of ultrasounds and her maternity shots, he might not have long to wait at all.

Whether it's a little brother or a sister who's on the way is as yet unclear.