I throw them in the washer and dryer...I would never wear an underwire bra so I have no toruble with them in the washer or dryer....I don't hand wash anything
I hand wash them and hang them to dry. I've done both, and hand washing definitely makes them last longer. If I have a cheap (around $15) bra, I will throw it in the wash, but my nursing bras are all around $35. That's way too expensive to let them break, and hand washing doesn't take much time.
use one of those mesh zip lingerie bags and throw them in the washer. They won't get quite as mangled as they would without the bag, so it might increase the longevity at least a bit.