In most women, BV causes no harm whatsoever, though the discharge may be unpleasant and distressing at times.

However, women with untreated BV during pregnancy have a slightly higher risk of premature labour, miscarriage, preterm birth and having a baby with a low birthweight. Pregnant women who suspect they could have BV should see a GP, midwife or obstetrician.

BV can also cause complications in women who have had recent gynaecological (pelvic) surgery- the chance of developing an infection of the womb is slightly higher.

There is also some evidence that women with untreated BV may be at an increased risk of getting other STIs and Pelvic Inflammatory Disease (PID).