Bacterial vaginosis (BV) is caused by an overgrowth of bacteria in the vagina. The presence of a variety of bacteria in the vagina is normal and most are harmless. BV occurs when there is a change in the balance of these bacteria, allowing some to multiply more than others. This is normally due to an alteration in the vagina's pH levels. BV is not caused by poor hygiene and can often be a result of excessive washing. The causes of bacterial imbalance in the vagina are not fully understood. However, contributing factors can include:

• Using perfumed or antiseptic soaps and bath additives
• Using a douche or vaginal deodorant
• Using an intrauterine contraceptive (IUD)
• Having multiple sexual partners
• Hormonal changes during the menstrual cycle
• Smoking.

BV has been linked to a number of other conditions. It may increase the risk of some STIs, such as gonorrhoea. Pregnant women with BV may also be at increased risk of developing complications such as pre-term birth, low birthweight babies and waters breaking prematurely.

Smoking is a contributing factor to bacterial vaginosis

What are the symptoms?

BV can be very mild and have no symptoms, meaning that a woman may not even realise she has the condition. If present, the main symptom of BV is a change in vaginal discharge, which may:

• Appear white or grey in colour
• Become thin and watery
• Develop a strong, fishy odour.

Left untreated, BV may resolve itself. However, some women find that it comes back time and again.