Brooklyn Decker recalls how she got a 104 fever and 'horribly painful' mastitis because of an underwire bra. Here's how that can happen.

• Brooklyn Decker told People that she got mastitis eight months postpartum.
• Decker said she was wearing underwire bras at the time, which her doctor said may have caused it.

Brooklyn Decker got mastitis, an inflammation of breast tissue typically caused by an infection, from wearing an underwire bra on set, the actor said on People's "Me Becoming Mom" podcast.

Decker currently stars on Netflix's "Grace and Frankie," and gave birth to two children in 2015 and 2017, respectively. On the podcast, she spoke about the stress of breast feeding after the birth of her first child, Hank, as well as a brush with mastitis that she had postpartum, which she said was likely due to her undergarments.

"What I didn't realize until I had mastitis — eight months postpartum with a 104 fever, it was horrible — which I should have known, was that underwire bras can cause mastitis and can affect milk production, and let down, and all of that," Decker told People's Head of Digital Zoë Ruderman on the podcast.

Mastitis, a condition where the breast tissue becomes inflamed and sometimes infected, can cause swelling, redness, pain, and even a fever and chills, according to the Mayo Clinic.

"It was painful, but what was wild was that it was almost as if I was in a fever dream," Decker said. "I was so loopy from such a high fever, and I was having so much pain, and I couldn't put my arm down, and it was so hot."

Bras with underwire can increase the risk of mastitis, experts say

People who are breastfeeding are more likely to experience mastitis, since it can cause clogged milk ducts and bacteria to get into the breast.

Underwire bras can increase a person's risk of developing mastitis, according to breastfeeding education and awareness organization La Leche League International. This type of bra has a firm structure, which can restrict the breasts and cause a clog. Too-tight bras, even without underwire, can have the same effect, according to La Leche League.

Decker said that at the time, she was wearing underwire bras, given that she was shooting and in production. According to Decker, her doctor said that "this late in the game" underwire, sitting on a breast duct, could cause mastitis.

It doesn't matter how far a person is into nursing for a too-tight bra to contribute to mastitis, certified lactation counselor and educator Ashley E. Davis told Insider.

According to Davis, so long as a breastfeeding parent is producing milk, there's a chance for a duct to become clogged. In addition to bra tightness and underwires, Davis said not pumping often enough can lead to mastitis.

She suggested breastfeeding parents wear tanks and bras specifically designed for nursing for as long as possible, and ideally for the entire breastfeeding period.