 In hypoestrogenic women, the vaginal microbiome shifts from low diversity communities, commonly dominated by Lactobacillus, to more diverse communities dominated by anaerobes; this change can be reversed with estrogen treatment. Since the FUM of women with OAB includes bacteria similar to those of the vaginal microbiome e.g. Lactobacillus, Gardnerella, and diverse anaerobes, the investigators reason the FUM would respond similarly to estrogen and become less diverse. Although transvaginal medications likely alter nearby bacterial niches e.g. the bladder, no study has reported the urinary microbiomic response to vaginal estrogen. 