Douching, but not other feminine hygiene behaviors, is probably a significantl cause of bacterial vaginosis, that is, it is not simply a response to BV symptoms.Douching compared with other feminine hygiene behaviors:

After adjusting for demographic and sexual behavior factors, neither type of underwear (nylon vs. cotton prevalence ratio (PR) 1.05, 95% CI: 0.97–1.13), menstrual protection (tampons vs. pads; PR: 1.04, 95% CI: 0.95–1.12; pads and tampons vs. pads 1.00, 95% CI: 0.92–1.07), use of pads or panty liners when not menstruating (PR: 0.99, 95% CI: 0.95–1.05), nor weekly or greater use of hygiene spray (PR: 1.01, 95% CI: 0.94–1.09), powder (PR: 1.02, 95% CI: 0.96–1.07) or towlettes (PR: 1.03, 95% CI: 0.94–1.13) were strongly associated with BV. PR for daily versus less than daily bathing and showering were 1.06 (95% CI: 1.02–1.12) and 1.04 (95% CI: 1.00–1.09). Douching remained associated with BV (PR for weekly or greater vs. never 1.17, 95% CI: 1.09–1.26) and was not substantially impacted by adjustment for other hygienic behavior.

Klebanoff MA, Nanse TR, Brotman RM, et al. "Personal Hygienic Behaviors and Bacterial Vaginosis." Sexually Transmitted Diseases:  February 2010 - Volume 37 - Issue 2 - pp 94-99