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Take a look down at the girls: Is your bra doing you any favors?

“When women are wearing the wrong size, they can be miserable and uncomfortable,” Christina Faraj, a bra fit expert in Beacon, New York, told Fox News. “Clients tell me that if they’re not comfortable, they don’t stand up straight and aren’t confident. They just don’t feel good.” (However, while breast size may contribute to back pain, some studies suggest that bra fit doesn't.)

Plus, the right or wrong bra also affects how your clothes look and fit. Getting the size right will properly support your breasts, prompting your shoulders to push back. The better posture leaves your waist more exposed, so you look thinner. “It’s an instant change that happens,” Faraj said.

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Know that you can be a different size in different bras, even those within the same brand. Your body also changes as you age, and so what fit you a decade ago won’t necessarily now, Helen Mears, head designer at Adore Me, told Fox News. It’s worth it to get a proper fitting from a professional bra expert to confirm your correct size, she added.

Until then, here are four signs you’re wearing the wrong size:

1. The bra is rubbing (and chafing!) in certain spots.
Even though most people think this is from a too-tight bra, it’s actually because the band is too lose, Faraj said. “This causes the bra to move around, causing irritation.” Your bra should fit relatively snug and stay put.

2. The straps are falling off your shoulders.
The problem of having a too big band can also cause the wayward strap issue. As the band rides up in back, your straps can fall down. You may have to go down a band size (and perhaps up a cup size), Faraj said. This can also happen if you’re sporting a bra that’s old and worn out. As the elastic in the strap experiences wear and tear, it will loosen, Mears said.

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3. Your boobs are popping out of the cup.
Breast bubbles or a “double bust” point to a pretty obvious cause — cups that are too small, Mears said. (Same with if the middle of the front of the bra isn’t sitting flat on your sternum.) Try the next cup size up.

4. The fabric is wrinkling. If you have a smaller chest, you may notice that the fabric on the cups is a little wrinkly. “That’s because your breasts aren’t pushing the cup out and utilizing it fully,” Mears said. Even if you wear a smaller size, you still need support. Going down a cup size for a more snug fit will do the trick.

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