How often should you wear a fresh bra?

This is more: Personal issue than medical . As long as your body and the garment is clean you may change it as you find it fit . There is no set rule as to how frequently this kind of personal items should be changed . They should be individualized . In lactating moms , they need to be changed probably several times a day

Consider changing: Bra daily if you perspire heavily under breasts, have odor /fungus under breasts (ie. Intertrigo), are working out arduously or are lactating.