Breastfeeding requires a number of adjustments to your daily life -- including, possibly, changing the type of bra you wear. A bra that fits too tightly could affect your milk supply and might also leave you more vulnerable to blocked milk ducts and breast infections, medically termed mastitis. Your bra should be supportive but not too tight.
Effects on Supply
Wearing a very tight bra puts pressure on the milk ducts, which blocks the flow of milk through them. Because milk doesn't leave the ducts, it could send a message that no more milk is needed, which slows milk production. Anything that puts pressure on the milk ducts -- which extend back to your rib cage and as far up as your armpits -- can affect the milk ducts, pediatrician and author Dr. William Sears warns. Wearing a bra that's too tight, lying on your stomach or using a sling whose rings press into your breast tissue can decrease your milk supply by putting pressure on the ducts, certified breastfeeding educator Cheryl Taylor explains on Dr. Jay Gordon's website.
Increased Susceptibility to Mastitis
When bras that are too tight or constricting cause milk to stagnate in blocked milk ducts, it sets up for an increased risk of infection. Infection can occur in the ducts when bacteria enter the milk ducts through cracks in the nipple, although infection can occur even if you don't have obvious irritation or cracks, MayoClinic.com cautions. If you develop mastitis, you can continue to nurse on the affected side; in fact, if you don't, the infection can worsen.
The Perfect Nursing Bra
Finding a nursing bra that offers good support without putting too much pressure on the milk ducts can take some experimentation. You will almost certainly increase a cup size or two when you first start breastfeeding. Underwire bras can provide support for your heavier breasts but can also put pressure on the milk ducts. If you use a sports bra or other stretchy non-nursing bra, which are easy to push up for a feeding and then just pull back down, avoid bras that compress the breast tissue, similar to a breast binder.
If You're Bottlefeeding
If you've decided to bottle-feed your baby, your friends might suggest wearing a tight bra to decrease your milk supply. But it's better to wear a supportive but not too-tight bra when trying to decrease milk supply after delivery or if you're weaning your baby abruptly. A too-tight bra can decrease your milk supply, but can also increase your risk of developing blocked ducts and mastitis. Instead, use cold cabbage leaves and cold packs to relieve discomfort and decrease swelling.