No one should be surprised that Christina Aguilera had a boob job, or plastic surgery for that matter. This former Disney star has had breast implants multiple times to vary up her breast size. Before cosmetic surgery, Christina Aguilera was just an A cup. But, she went from a C to a 38DD cup during pregnancy; of course her bra size went back down after she gave birth. Here we can see Christina Aguilera before and after her first boob job transformation.
She's a C cup in the after picture here.
Here she is after having the plastic surgery for the second time. Her breast size is a solid D cup here.
Here's the breast implant scar under her right armpit.
Here's Christina Aguilera during her pregnancy at the peak of her breast size.