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Ill-fitting bras may cause breast tissue to migrate to one's armpit, back, and/or side.[1]

Migrated breast tissue, or MBT, is breast tissue that has, over time, shifted away from the breast mound to settle in the armpits or back, often even resulting in rolls. This is often the result wearing a poorly-fitting bra with too-small cups and a too-large band. However, migrated breast tissue can be corrected over time by wearing a well-fitting bra and gathering all the migrated tissue into the cups each time a bra is worn, using the scoop and swoop.[2][3]

There are also reports that breast tissue can migrate to the center of the chest, resulting in poor division between the breasts.[1]


One common cause of breast tissue migration is constant use of an ill-fitting bra; specifically, for migration to the back and armpits, bras with too-small cups and a too-large band. When wearing such a bra, the tissue in the breast mound squeezes out the back and sides of the cups, into the armpits. Over time, this tissue moves more permanently into the areas into which it has been pressed.

Bras with a too-large cup may cause tissue migration to the sternum.[4]


Main article: Scoop and swoop

Migrated breast tissue can be gradually moved back towards the breast mound by wearing a well-fitting bra and regularly "scooping" the migrated tissue into the cups.[5] Correction of serious breast tissue migration may result in a change of size,[4][6][7] namely down in band size and up in cup size.