Researchers do not know the cause of BV. However, we do know the condition most often occurs in those who are sexually active. BV is a result of an imbalance of “good” and “harmful” bacteria in a vagina. Douching, not using condoms, and having new or multiple sex partners can upset the normal balance of vaginal bacteria, increasing your risk for getting BV.
We also do not know how sex causes BV. There also is no research to show that treating a sex partner affects whether someone gets BV. Having BV can increase your chances of getting other STDs.
BV rarely affects those who have never had sex.
You cannot get BV from toilet seats, bedding, or swimming pools.