This is a myth that needs to finally be put to rest: Having a bra that is too tight, too small, underwired, or filled with air pockets or water doesn't contribute to someone developing breast cancer. But while we're on the subject of bad-fitting bras, please know that they can cause other issues—and not just because a too-small bra (either in circumference or cup size) is uncomfortable.

Photographs of models wearing bras are not what you want to be studying while trying to determine if a bra looks good and fits properly on you. If you look the way those models do, then you're probably looking at a bra that doesn't fit. Frontal spillage may be sexy and alluring, but it's not good for your body—especially your back. And women who are hoping to breastfeed can have their own difficulties as well, due to the blood supply potentially being more constricted.

So, when bra shopping, ask the manager of the lingerie department if they have a certified fitter, either on the premises or at another location. A fitter can properly measure you and help you select bras that will best match your body type, breast size, and contours.

But rest easy: Bad-fitting bras won't lead to breast cancer.

Is it okay to occasionally wear a bra that is clearly smaller than adequate, so you can show off your cleavage? Sure, once in a while ... But don't make it a habit! And if you have young girls you are raising, now is the time to set a good example.