Bacterial vaginosis (BV) is caused by an imbalance in the natural bacteria of the vagina. Normally, "good" bacteria called lactobacilli outnumber "bad" bacteria (anaerobes). BV occurs when there is an overgrowth of harmful bacteria such as Gardnerella vaginalis and other anaerobes, which disrupts this balance

. Several factors can trigger this imbalance, including:

• Douching, which disrupts the natural vaginal environment

• Having a new or multiple sexual partners, which can introduce different bacteria and alter vaginal flora

• Not using condoms consistently, increasing risk of bacterial imbalance

• Use of vaginal deodorants, scented soaps, or perfumed products around the vagina

• Having an intrauterine device (IUD), especially with irregular bleeding

• Hormonal changes during pregnancy or reproductive years

• Recent antibiotic use, smoking, stress, and poor diet can also increase risk by affecting bacterial balance or immune response

While BV is more common in sexually active women, it can occur in women who have never had sex, though rarely

. BV is not classified as a sexually transmitted infection, but sexual activity can increase the risk

. The exact mechanism of how sex influences BV is not fully understood

. In summary, BV is caused by a disruption in the vaginal bacterial balance, often triggered by behaviors or conditions that alter the vaginal environment or introduce new bacteria