Bacterial vaginitis, when combined with pregnancy, can affect both the fetus and the pregnant woman, as it can manifest as increased vaginal discharge, yellowish color, odor, and vulvar itching. In the case of the fetus, there is a tendency for upstream infection and pre-eclampsia, or for the embryo to stop developing. Metronidazole can be used vaginally at this time because it is very effective in treating bacterial vaginitis. Moreover, topical application of metronidazole in the early stages of pregnancy does not affect the fetus. If the bacterial vaginitis is caused at any other time of pregnancy, metronidazole can be applied topically. It is also safe to apply metronidazole orally after more than 3 months of pregnancy.