The vaginal microbiota in pregnant Brazilian women: its characterization, risk factors, and association with adverse pregnancy outcomes

Abstract

The microbiota, or communities of bacteria living in and on the human body, is increasingly recognized to play a role in human physiology and health. It is now known, for example, that bacteria colonizing the vagina help to defend against opportunistic infections and maintain homeostasis of the vaginal niche. The absence of vaginal homeostasis (dysbiosis) may lead to infection and predispose pregnant women to adverse reproductive outcomes. At the same time, considerable variation in the vaginal microbiota has been documented across populations, and such variation may likewise influence reproduction and health. Despite evidence for such associations accumulating in the literature, few relevant studies have been carried out in South America, including Brazil. As part of an ongoing thematic project funded by FAPESP, we propose to recruit 100 adult pregnant women at d18 weeks of gestation from 33 Health Care Units in Araraquara, SP. We will collect vaginal samples from participants at three points in pregnancy (d18, 20-26, 30-36 weeks) in order to model vaginal microbial community composition and its variation across gestation. In addition to characterizing the vaginal microbiota of pregnant Brazilian women, next-generation 16S ribosomal RNA gene sequencing and bioinformatics analysis will be used to test for associations between the microbiota and preterm birth, low birth weight, and intrauterine growth restriction. The latter two outcomes remain critically understudied in this context. We will also assess effects of sociodemographic, lifestyle, and clinical/reproductive factors of participants on the vaginal microbiota, in order to identify potential risk factors for microbial changes associated with adverse pregnancy outcomes. (AU)