When scientists do research on the effects of an unpopular name, we're afraid that Mildred is one of the examples they city, often in tandem with Bertha and Gertrude. But with cute nickname Millie on the rise, anything's possible.
Mildred is an ancient Anglo-Saxon name that became popularized in England via an eight century saint. In the US, she was a Top 10 choice from 1903 to 1926. A literary/cinematic Mildred is James M.Cain's noir protagonist Mildred Pierce, portrayed on screen by Joan Crawford in an iconic role. Mildred Bailey was a great jazz singer.