A healthy vaginal microbiome is characterized by the presence of only lactobacilli that acidify the vagina and protect against infections such as HIV and human papillomavirus (HPV, the virus causing cervical cancer). Bacterial vaginosis (BV) is a disturbance of this healthy vaginal microbiome whereby lactobacilli are absent and anaerobes such as Gardnerella vaginalis and Atopobium vaginae predominate. BV is prevalent in about one quarter of women of reproductive age in SSA and has been associated with adverse pregnancy outcomes such as preterm birth (PTB) and neonatal sepsis. PTB is the main cause of neonatal mortality. However, the microbiological determinants that link BV with adverse pregnancy outcomes are not understood. G. vaginalis is considered a key pathogen of BV as it is found in nearly all women with BV and has virulence characteristics that explain the symptomatology of BV. However, the role of G. vaginalis is controversial as G. vaginalis is also found in women with a healthy vaginal microbiome. We recently shed more light on the role of G. vaginalis by studying the complete genomes of different Gardnerella strains and showed that G. vaginalis actually comprises 13 different species, with different virulence characteristics. Three of these have been officially published as new species, i.e. G. piotii, G. leopoldii and G. swidsinskii. In this project, we aim to study the vaginal microbiome, including the recently described Gardnerella species, in African women in relation to PTB.