The 7 Bra Myths You've Got to Stop Believing

We all wear bras, all day every day, and yet there are still so many contradictory facts about what's good and what's not. In fact, there's so much underthings-folkloregoing around that it's like our bras (which according to said folklore could very well be the wrong size) are out to get us.

To help answer the questions that plague us on a regular basis, we looked to bra expert and author of The Bra Book Jene Luciani. Here are the biggest myths she wants to debunk, stat:

1. Bras can endanger your health. This is a prevalent and equally unnerving belief that women have been fretting about for over 20 years. It began with a 1991 case study that found women who didn't wear bras had a lower risk of breast cancer than those who did. Even though the scientists who conducted the study believed it was actually due to factors connected to wearing a bra, rather than the bra itself, it still set off alarms.

"They believed that that too-tight underwire compressing mammary glands could trap toxins." explains Luciani, who researched it at length for her book. "But there is no scientific evidence to back up this claim."

2. Sleeping in a bra makes breasts perkier. Women tend to be split right down the middle on this matter. The first half faithfully keep their bra on through the night—some for comfort, others because they firmly believe it's the secret to flouting the forces of nature—and the other half hardly make it home before unclasping that baby. Sorry to disappoint the former, but sleeping in your bra is not what's going to keep 'em pert. What will? "Wearing a supportive bra over time can help, especially when exercising and breasts are significantly stretching or bouncing up and down," says Luciani. "Other than that, there aren't many ways to really avoid it." Le sigh.

3. Bras have fixed sizing. Much like a size 6 dress can yield varied interpretations across different clothing retailers, bra brands have different sizing. "Unfortunately, there is no consistency at all," says Luciani. "Each brand has their own 'fit model'. Plus, you can be a different size for several styles within the same brand." To ensure you don't walk out of the store with something that doesn't fit, get fitted on-site and try on several, and we mean several styles.

4. The letter determines the size of the cup. If you've ever heard the term "sister size" at a bra fitting, it's because another style can hold the same volume of cup (i.e. density of boob) depending on band size. "The letter correlates with the cup size," says Luciani. "However, that is determined based on the calculation between the two measurements." Word to the wise: Even if you were an ace in calculus back in high school, always leave the math to your bra specialist.

5. The average bra size is in the B range. In reality, it's larger (Luciani estimates that it's somewhere around a C), but this myth sheds light on a bigger problem: women often wear the wrong bra size. "Many women are fitting themselves into the sizes most commonly found in stores instead of getting a proper fitting and a truer size," says Luciani. "On top of that, bra makers know what sizes tend to sell the most, and so those become the 'average' sizes." Full disclosure: As conscious as we try to be about wearing proper bras, we're so guilty of the grab-and-go when we hit the stores.

6. You can just throw your bras in the washing machine. Picking up our dry-cleaning is trying enough—handwashing our underthings is the last thing we want to add to the list. Alas, the well-being of our bras, and thus our cleavage, could be at stake. "The center drum can crush cups and stretch straps if they snag on them and hot water can break down the elasticity of the bra" says Luciani. "So, if you want to go the machine route, hook the bra and place into a mesh bag and wash in cool water with a gentle detergent." The best option though is to handwash your bras by soaking them in a sink with lingerie wash, like Tocca Stella Laundry Delicate ($15), and lay them out flat to dry.

7. You only need to wash your bra once a week. It looks like we could all be a bit more hygienic in this regard. "The dirt and oil in our skin can break down the elasticity of the bra," explains Luciani. "So it's best to wash as often as possible." If laundry day occurs less often than you'd like to admit (don't worry, we're with you), there's an easy workaround: Add more bras to your repertoire!

Follow Marie Claire on Instagram for the latest celeb news, pretty pics, funny stuff, and an insider POV.