When a woman gives birth, her breasts tend to swell in preparation for newborn baby feeding, however after the breastfeeding frenzy is over, they tend to shrink back to their original size within just a matter of days.
Why does this happen?
In the journal Developmental Cell, researchers determined that the cells inside the breasts will end up consuming dead cells around them, so in short, they're actually eating themselves down to size.
Interestingly, this is probably a good thing since women see an increased risk of breast cancer following pregnancy. By getting rid of most of the unnecessary dead cells, the body enacts its own prevention mechanism against cancer by removing the breeding ground for cancer cells.