The relationship between the anti-Porphyromonas gingivalis immunoglobulin G subclass antibody and small for gestational age delivery: a longitudinal study in pregnant Japanese women

Untangling Associations of Microbiomes of Pregnancy and Preterm Birth

This review illuminates the complex interplay between various maternal microbiomes and their influence on preterm birth (PTB), a driving and persistent contributor to neonatal morbidity and mortality. Here, we examine the dynamics of oral, gastrointestinal (gut), placental, and vaginal microbiomes, dissecting their roles in the pathogenesis of PTB. Importantly, focusing on the vaginal microbiome and PTB, the review highlights (1) a protective role of Lactobacillus species; (2) an increased risk with select anaerobes; and (3) the influence of social health determinants on the composition of vaginal microbial communities.

Oral microbiome and preterm birth

Background

The etiology of preterm birth (PTB) is heterogeneous and not yet well known. Maternal periodontal disease has been investigated for decades and is a known risk factor for adverse pregnancy outcomes. However, no particular bacterial species or higher taxonomic order has been found as causative of PTB, leading to studies of the whole oral microbiome. In order to determine if and how the composition of the oral microbiome is associated with PTB, we performed a large case-control study including women with term (TB) and PTB.

Methods

We compared oral microbiomes in PTB to TB, to examine differences in the microbial richness, diversity, and differential abundance of specific taxa. We obtained oral swab samples from 152 Caucasian pregnant women who were classified as either PTB (≤36 6/7 weeks, n = 61) or TB (≥38 0/7 weeks, n = 91) in exclusion of any other major medical or obstetric conditions. The oral microbiomes of these women were characterized by 16S ribosomal RNA (rRNA) gene sequencing of the V3-V4 region on the MiSeq platform.

Results

The dominant microorganisms at the phylum level in all pregnant women regardless of birth week outcomes as belonging to Firmicutes, Proteobacteria, Bacteroidetes, Fusobacteria, and Actinobacteria. The phyla Firmicutes and Bacteroidetes were relatively more abundant in women with a PTB than in women with a TB, while Proteobacteria was less prevalent in women with a PTB. At the genus level, Veillonella, Prevotella, and Capnocytophaga were enriched in the PTB, and while many of the members of these genera could not be resolved to the species level, Veillonella massillensis was shown to be increased in the PTB group.

Conclusion

We identified the genera Veillonella, Prevotella, and Capnocytophaga in the maternal oral microbiome as being associated with PTB independently of clinically apparent infection, uterine anomalies, and other pregnancy complications, including placenta previa, and placental abruption. The clarification of the role of those taxa in the etiology of PTB merits further research.

Oral Anaerobic Microflora and Pregnancy Complication

Bacterial vaginosis and periodontal diseases share very similar pathogenesis. Each of these diseases occurs when healthy microbiome changes to predominately anaerobic bacterial flora. Bacterial vaginosis is proven factor for adverse pregnancy outcomes. In recent years it has been hypothesized that infection from distant sites of the fetoplacental unit may also elicit an inflammatory response in utero. Aim: The study is designed to determine whether the presence of specific oral anaerobic bacteria in subgingival sulcus of mother increase the risk of adverse obstetric outcomes. Material and Methods: Case-control study.  Control group: 50 patients who gave birth to neonate whit normal birth weight at term. Group cases: I group - 40 pregnant women who were hospitalized with signs of preterm labor. II - 20 pregnant women, who have an ultrasound diagnosis of fetal growth retardation. Sub-gingival microbiological paper-point swab was taken in all patients. Results: The total number of isolated oral anaerobic bacteria was statistically significantly higher in the cases group compared to control group p <0.01. In our study, pregnant women who tested positive for Porphyrmonas gingivalis for 6.65 times were more likely to have preterm labor compare with pregnant women with negative oral swabs (95.0% CI: 1.38-32.11 / p <0.05), and for 2,79 times more likely to have fetus with intrauterine growth restriction (95.0% CI: 1.10-7.91 / p <0.05 Conclusions: The study confirmed the hypothesis of a statistically significant association between oral anaerobic infection and adverse pregnancy outcomes. In the future, more studies are needed to investigate the role of the microbial load, maternal immune response, pathophysiological pathway that leads to negative pregnancy outcome.  

The Role of Microbiota in Infant Health: From Early Life to Adulthood

From early life to adulthood, the microbiota play a crucial role in the health of the infant. The microbiota in early life are not only a key regulator of infant health but also associated with long-term health. Pregnancy to early life is the golden time for the establishment of the infant microbiota, which is affected by both environmental and genetic factors. Recently, there is an explosion of the studies on the role of microbiota in human diseases, but the application to disease or health is relatively limited because many aspects of human microbiota remain controversial, especially about the infant microbiota. Therefore, a critical and conclusive review is necessary to understand fully the relationship between the microbiota and the health of infant. In this article, we introduce in detail the role of microbiota in the infant from pregnancy to early life to long-term health. The main contents of this article include the relationship between the maternal microbiota and adverse pregnancy outcomes, the establishment of the neonatal microbiota during perinatal period and early life, the composition of the infant gut microbiota, the prediction of the microbiota for long-term health, and the future study directions of microbiota.

Effect of Oral Prophylactic Measures on the Occurrence of Pre-Eclampsia (OP-PE) in High-Risk Pregnant Women: A Cluster Randomized Controlled Trial

Pre-eclampsia (PE), a pregnancy-specific hypertensive disorder, characterized by the development of placental endothelial dysfunction, remains a major source of maternal and perinatal morbidity and mortality, especially in low- and middle-income settings. Periodontal disorders during pregnancy, and particularly periodontal pathogens, may be related to the risk of PE. Standard oral hygiene methods, based mainly on the joint use of toothbrushes and interdental brushes, reduce periodontal inflammatory risk and modulate the dysbiosis of the oral microbiome. The aim of this trial is to compare the PE outcomes in high-risk pregnant women receiving oral prophylactic measures to a control group. This trial is designed as a two-arm, parallel, cluster randomized controlled trial with the antenatal obstetric clinic as the unit of randomization and an allocation ratio of 1:1. The pregnant women will be included at 3 months of pregnancy and will be followed throughout the pregnancy. The primary outcome measure will be the incidence of PE from a baseline during the pregnancy. Secondary outcomes measures will include changes from the baseline in quantification of the pathogenic bacterial load of the interdental microbiota, the severity scores of periodontal indicators, and the incidence of adverse perinatal outcomes. This trial should demonstrate that the implementation of daily oral hygiene reduces oral dysbiosis, the incidence of periodontal disease, and the risk of PE.

Oral microflora and pregnancy: a systematic review and meta-analysis

Understanding changes in oral flora during pregnancy, its association to maternal health, and its implications to birth outcomes is essential. We searched PubMed, Embase, Web of Science, and Cochrane Library in May 2020 (updated search in April and June 2021), and conducted a systematic review and meta-analyses to assess the followings: (1) oral microflora changes throughout pregnancy, (2) association between oral microorganisms during pregnancy and maternal oral/systemic conditions, and (3) implications of oral microorganisms during pregnancy on birth outcomes. From 3983 records, 78 studies were included for qualitative assessment, and 13 studies were included in meta-analysis. The oral microflora remains relatively stable during pregnancy; however, pregnancy was associated with distinct composition/abundance of oral microorganisms when compared to postpartum/non-pregnant status. Oral microflora during pregnancy appears to be influenced by oral and systemic conditions (e.g. gestational diabetes mellitus, pre-eclampsia, etc.). Prenatal dental care reduced the carriage of oral pathogens (e.g. Streptococcus mutans). The Porphyromonas gingivalis in subgingival plaque was more abundant in women with preterm birth. Given the results from meta-analyses were inconclusive since limited studies reported outcomes on the same measuring scale, more future studies are needed to elucidate the association between pregnancy oral microbiota and maternal oral/systemic health and birth outcomes.