Rose is expecting the couple's first child together early next year (13) and she has been sharing pictures of her growing belly with fans online.
She tweeted a photo of her rapper beau resting beside her expanding tummy on Wednesday (14Nov12), alongside the caption, "My sweetheart fell asleep rubbin (sic) my belly he's the cutest".
The sweet snap immediately caught Cyrus' attention and she sent back the message, "that is actually the most adorable photo I have ever seen! Dayummmm (sic) that baby is gonna be beautiful."
And Rose was so touched by the unexpected note, she invited the former Hannah Montana star and her fiance, Australian actor Liam Hemsworth, to help take care of the tot once it's born.
Rose replied, "aww Miley aren't u a sweety pie! Thx (thanks) babes u and Liam can babysit anytim (sic)".