Abstract: Disclosed herein are embodiments of a method for using estrogenic compounds to manipulate the bacterial composition of vaginal communities of female subjects. The method may include titrating a dose of an estrogenic compound to provide a female subject with a personalized effective dose, such as a minimum effective dose, sufficient to attain and/or maintain one or more determined target values of a relative abundance of vaginal Lactobacillus in the vaginal microbiota, an absolute abundance of vaginal Lactobacillus in the vaginal microbiota, a vaginal pH, a vaginal lactic acid concentration, or any combination thereof.