So many bras these days are constructed with underwire, that women are becoming increasingly convinced that all bras should have an underwire. But then, why would most companies still offer several non-underwire options to their customers? I’m going to help solve the mystery of what an underwire actually does for you.
Let me start with one of the basic principles of bra fitting (you can see my other blogs on this by clicking here). When your bra fits properly, the underwire should contour all of your breast tissue (from under your arms to where your cleavage resides) and lay flat against your breastbone in the front, without constraining your breasts or rubbing against your skin.

Dahlia bra and panty set by Valisère (Triumph). Size range: 34-40, D-DD cups. Available at Now That's Lingerie.com.
The purpose of an underwire is to contour the natural shape of your breast by encompassing the entirety of your breast tissue and giving it lift and a round shape. When encased in those cups, your breasts will only be supported to the extent that the fabric of your cup covers your breasts. For example, let me compare two distinct types of underwire bras. If you’re wearing a padded push-up bra (most of which offer only minimal support), you are getting less support than if you were wearing a full cup minimizer (intended to deliver the utmost support). But both bras have underwire. So what determines this difference in support levels?
For any bra, the straps, elasticated back band, fabric, stitching, underwire and coverage all work together to play a crucial role in perfecting your comfort. The majority of the support of a properly fitted bra lies in the elasticity (or firmness) of the fabric of your cups, plus the stitching (if any) on or along the cups. (The reason I emphasize properly fitted is because, if your bra doesn’t fit, it doesn’t matter what style you’re wearing– you will not be get the support that the physics of your bra intended! Click for more of my blogs on bra fitting.) So, if your bra cups only cover half of your boobs (like in a demi-cup or demi-bust bra), then chances are, your bra won’t give you as much support as a full-coverage bra– regardless of whether there is or isn’t an underwire. This also means that a bra with a stretchier fabric on the cups will support your breasts less than a bra made with a sturdier, less extensible fabric.
So that’s part of understanding what underwire can do for you. Before I continue, I want to make something clear. Just because you may prefer to wear non-underwire bras does NOT mean you are getting less support than a woman who wears underwire. Many non-underwire bras are equipped with a supportive elasticated band around the torso and have seams that are stitched internally in such a way as to provide shape and support. Full support bras DO exist without underwire and their support can be comparable to that of an underwire bra. The major difference is that the shape of your breasts will sometimes be different in either type of bra. You see, underwire works to envelop the entirety of your breast tissue, from beneath your arms and below your breast, bringing their weight closer to the front and slightly lifted upwards. Some non-underwire bras may constrain the breast tissue nearer to your body, but this may make your breasts seem smaller, especially since your breasts will seem less separated from each other than if there was an underwire contouring each breast.

The Vintage Touch wire-free bra by Warner's offers a naturally rounded fit and unparallelled comfort. Available at Now That's Lingerie.com
So what have you learned? Properly fitted, underwire bras help give you a more precise fit while supporting your breasts, but what more fully determines the support level are the fabric (and stitching) of your bra cups (more on this in a subsequent blog!). All these aspects (and more, like the strap’s width) work together to provide support. For women who do not like underwire bras and find them uncomfortable, don’t fret– there is still a wide range of non-underwired bras available for your comfort and convenience.
For all your bra fitting questions… contact me at celinethebradoctor@nowthatslingerie.com! I hear from dozens of women every week with a wide range of bra fitting issues, and I respond to them personally. So don’t hesitate or wait to feel comfortable in your bras.
See you next time!
Your Bra Doctor
bradoctor@nowthatslingerie.com