Here are some priorities when it comes to nursing bras:
•Good support. The bra should support your breasts, even when the flaps are open. If your breasts are very large, look for wide straps.
•Easy-open. You should be able to easily open and close the flap with one hand (and without looking).
•Breathability. You don't want moisture trapped near your nipples.
•Comfort. Make sure the bra isn't too tight and doesn't squeeze you in any one spot (this could lead to plugged ducts). Some moms have trouble with underwire bras, others don’t — try one on, and steer clear if it presses on your breast tissue.
If possible, head to a maternity shop, get measured by a specialist, and try on several bras. Some moms like to purchase at least one super-comfy "sleep bra" or nursing tank (with a built-in bra) along with a few for daytime wear. If you’re ordering bras online or from a catalog, follow the retailer's instructions for measuring your correct fit.
If you're bra shopping before baby arrives, start with one or two inexpensive nursing bras that are one cup size up from what you're wearing at the end of your pregnancy. These will get you through the first weeks until you have a better idea of your exact postpartum breast size.