Trichomoniasis is caused by a flagellated protozoan, Trichomonas vaginalis. It is always sexually transmitted.

Bacterial vaginosis is the most common cause of vaginitis, vaginal discharge or malodor. Its prevalence is similar in both pregnant and non-pregnant women.

Vulvovaginal candidiasis is caused by overgrowth of yeasts where 70-90% of cases are secondary to Candida albicans. It most commonly occurs when the vagina is exposed to estrogen (ie, reproductive years, pregnancy) and may be precipitated by antibiotic or corticosteroid use. Immunocompromised and diabetic women are also at risk.