Christina Aguilera has been revealing the secrets behind her impressive post-baby body.

The singer  — who gave birth to a son, Max, in January — even opens up about the eye-popping cleavage that she’s been flaunting about town in recent weeks.

And it sounds as if Xtina and husband Jordan Bratman are just as awed as the rest of us by her expanding chest.

"It's kind of hilarious! I've never fit into an E-cup before," she tells Us.

"I look at my husband and go, 'Guess what size this bra is?' And when I tell him, he's just amazed.

“We keep the tags that prove it, to look back for memory's sake!"

Xtina's stupendous chi chis can be found here!