I have done a tiny bit of research on the history of the bra today. Turns out that women have noticed a need to support their breasts, especially during work or sports, since the ancient Greeks or earlier. Some sites say the bra can be traced back as early as 2000BC.
Of course, we all know bras have been seen in many forms over the years. Apparently the Minoan women of ancient Greece wore bikini-like clothing when participating in sports. Some societies emphasized the breasts and exposed them, while others kept them covered with loose cloth.
The bra as we know it started more as a replacement for uncomfortable corsets. Many of the sites I checked out credit France for the first bras, as well as the name which is short for brassiere, meaning support. While you always hear that men designed the first bras, the oldest US patents for bras, or breast supporters, were given to women. Men were more likely to be the designers of corsets, with their heavy steel construction, but women made the bras. In fact, ever wear a Warner brand bra? Their original bra patent was purchased from Mary Phelps Jacobs and consisted of silk handkerchiefs and ribbon. Warner is also credited with introducing the alphabet system of cup sizing.
Another bra pioneer who introduced cup sizing was Ida Rosenthal, creator of Maidenform. She believed in getting girls while they were young (training bras) to keep their loyalty as they aged.
Considering how much we complain about bras, a look at bra history really shows how far we've come. At least we aren't expected to wear corsets (although some people still choose to). We aren't expected to hide them, or completely expose them, depending on the fashion whims. We get to choose how much or how little they are exposed.
We also are lucky enough to be around for the expanding cup size revolution. Before Ida and Warner, bras were made in small, medium and large. Then came A, B, C and D, and eventually AA and DD. Now look at us! We have Gs and even Ms if you look hard enough. We have large cups with small bands and small cups with larger bands. We have so much choice in our bras, from utilitarian nylon and cotton to barely useful lace.
Before I close, I will post some links of the sites I checked out on bra history. I found them in a simple Google search using the term "bra history".