A new article published in Fertility and Sterility reported that the vaginal microbiota, in many instances, is dominated by the Lactobacillus species. Some women may be lacking in Lactobacillus spp. in their vagina, and instead may harbor a wide array of strict and facultative anaerobes. This state has been associated with an increased risk for infection, disease, and poor reproductive and obstetric outcomes. The authors discussed that the level of protection against infection can also vary by species and strains of Lactobacillus, and that some species, although dominant, are not always optimal. Sub-optimal or inadequate amounts of beneficial bacteria in the vagina may predispose to the risk of contracting sexually transmitted infections and may influence the occurrence of adverse reproductive outcomes, such as tubal factor infertility. Hence, it was stated that the composition and function of the vaginal microbiota plays a major part in pregnancy and fertility treatment outcomes.