The exact birth date of Leona Chalmers is difficult to pinpoint definitively, with conflicting information available. However, based on available records and patent application dates, it is highly probable she was born in the early years of the 20th century. Details about her early life, family background, and education remain largely undocumented.

Chalmers reportedly began working on early prototypes of a menstrual cup during the 1930s. While specifics of her initial experiments are scarce, it's believed she was driven by a desire to find a more comfortable and convenient solution for menstrual hygiene compared to the bulky and often uncomfortable options available at the time.