The Perinatal Microbiome and Pregnancy: Moving Beyond the Vaginal Microbiome

Abstract

The human microbiome, the collective genome of the microbial community that is on and within us, has recently been mapped. The initial characterization of healthy subjects has provided investigators with a reference population for interrogating the microbiome in metabolic, intestinal, and reproductive health and disease states. Although it is known that bacteria can colonize the vagina, recent metagenomic studies have shown that the vaginal microbiome varies among reproductive age women. Similarly, the richness and diversity of intestinal microbiota also naturally fluctuate among gravidae in both human and nonhuman primates, as well as mice. Moreover, recent evidence suggests that microbiome niches in pregnancy are not limited to maternal body sites, as the placenta appears to harbor a low biomass microbiome that is presumptively established in early pregnancy and varies in association with a remote history of maternal antenatal infection as well as preterm birth. In this article, we will provide a brief overview on metagenomics science as a means to investigate the microbiome, observations pertaining to both variation and the presumptive potential role of a varied microbiome during pregnancy, and how future studies of the microbiome in pregnancy may lend to a better understanding of human biology, reproductive health, and parturition.

Implications of caesarean section for children's school achievement: A population‐based study

“…15,16 Another mechanism could be the microbiome, where intestinal flora develop differently according to delivery mode (as the baby born by caesarean section does not pass through the bacterial milieu of the vaginal canal or is exposed to antibiotics routinely given at caesarean section), resulting in different postnatal development of the immune system. 17 Given the uncertainty and opposing nature of the hypothesised mechanisms, we held no a priori hypothesis about the direction of the effect of caesarean on schooling. Although we did not hypothesise a specific pathway towards schooling, this study excludes a large impact of delivery on child development.…”

Microbiome in normal and pathological pregnancies: A literature overview

“…The vaginal mucosa is a barrier that provides protection against pathogenic infections through the interaction between its epithelial cells, the immune system, and colonizing microorganisms (Figure ) . The composition of the female genital tract microbiota is influenced by many factors including age, vaginal pH, hormonal secretions, the menstrual cycle, contraceptives, antibiotic use, and sexual activity . The microbial composition of a woman′s genital tract varies over time, according to her estrogen production .…”

Cesarean birth is not associated with early childhood body mass index

“…The early life environment is thought to influence the development of obesity, with recent attention focusing on the microbiome. Inoculation of the newborn gut by vaginal and gastrointestinal microorganisms occurs during vaginal but not cesarean births, offering a potential mechanism linking cesareans with obesity . A recent systematic review suggested that cesarean was associated with 0.44 higher BMI (95% CI 0.17, 0.72) but was unadjusted for confounding .…”