Is there a role for probiotics in the prevention of preterm birth?

Pregnancy outcomes in pregnant women taking oral probiotic undergoing cerclage compared to placebo: two blinded randomized controlled trial

AIM

The purpose of this study is to evaluate the oral probiotic effect on pregnancy outcomes in pregnant women undergoing cerclage compared to placebo.

METHODS

This study was a double-blind randomized clinical trial undertaken in Yasuj, Iran. 114 eligible participants who have undergone cerclage were randomly divided to either receive probiotic adjuvant or 17α-OHP (250 mg, IM) with placebo from the 16th -37th week of pregnancy by "block" randomization method. Our primary outcomes were preterm labor (PTB) (late and early) and secondary outcomes were other obstetrical and neonatal outcomes included preterm pre-labor rupture of membranes (PPROM), pre-labor rupture of membranes (PROM), mode of delivery, and neonatal outcomes including anthropometric characterize and Apgar score (one and fifth-minute).

RESULTS

Results show that there are no statistically significant differences between the two groups in terms of PTB in < 34th (15.51% vs. 17.86%; P = 0.73) and 34-37th weeks of pregnancy (8.7% vs. 16.1%; P = 0.22), and mode of delivery (P = 0.09). PPROM (8.7% vs. 28.5%; P = 0.006) PROM (10.3% vs. 25%; P = 0.04) was significantly lower in patients receiving probiotic adjuvant compared to the control group. After delivery, the findings of the present study showed that there were no significant differences in newborn's weight (3082.46 ± 521.8vs. 2983.89 ± 623.89), head circumstance (36.86 ± 1.53vs. 36.574 ± 1.52), height (45.4 ± 5.34 vs. 47.33 ± 4.92) and Apgar score in one (0.89 ± 0.03 vs. 0.88 ± 0.05) and five minutes (0.99 ± 0.03vs. 0.99 ± 0.03) after birth.

CONCLUSION

Our result has shown that the consumption of Lactofem probiotic from the 16th week until 37th of pregnancy can lead to a reduction of complications such as PPROM and PROM.

Effect of vaginal probiotics containing Lactobacillus casei rhamnosus (Lcr regenerans) on vaginal dysbiotic microbiota and pregnancy outcome, prospective, randomized study

The intermediate bacterial microbiota is a heterogeneous group that varies in the severity of the dysbiosis, from minor deficiency to total absence of vaginal Lactobacillus spp. We treated women with this vaginal dysbiosis in the first trimester of pregnancy using a vaginally applied lactobacilli preparation to restore the normal microbiota in order to delay the preterm delivery rate. Pregnant women with intermediate microbiota of the vagina and a Nugent score of 4 were enrolled in two groups: intermediate vaginal microbiota and a Nugent score of 4 with lactobacilli (IMLN4) and intermediate vaginal microbiota and a Nugent score of 4 without lactobacilli (IM0N4), with and without vaginal lactobacilli at baseline, respectively. Half of the women in each group received the treatment. Among women without lactobacilli (the IM0N4 group), the Nugent sore decreased by 4 points only in the women who received treatment, and gestational age at delivery and neonatal birthweight were both significantly higher in the treated subgroup than in the untreated subgroup (p = 0.047 and p = 0.016, respectively). This small study found a trend toward a benefit of treatment with vaginal lactobacilli during pregnancy.

The function and mechanism of action of uterine microecology in pregnancy immunity and its complications

The human microbiota influences physiology, disease, and metabolic reproduction. The origin of uterine bacteria is controversial. The main assumption is that the germs enter the uterine cavity from the vagina through the cervical canal, bloodstream, fallopian tubes, and gynecological surgical channels. Understanding the microbiota at various anatomical sites is critical to the female reproductive system and pregnancy. Today's study focuses on the role of uterine bacteria in pregnancy and embryo implantation. According to our findings, the uterine microbiome influences embryo implantation and pregnancy outcome. Pregnancy is a natural, evolutionarily selected approach to human reproduction. During pregnancy, the microbiota of the reproductive tract changes, facilitating the maintenance of pregnancy, and the human immune system undergoes a series of changes that recognize and adapt to the non-self. From the beginning of pregnancy, a non-self fetus must establish a placenta of embryonic origin to protect itself and promote growth; the VMB tends to be more stable and lactobacillus-dominated in late gestation than in early gestation. Any material that disrupts this connection, such as microbial changes, is associated with a higher risk of poor health and poor pregnancy outcomes in women (eclampsia). The presence of any material that disrupts this connection, such as microbial changes, is associated with a higher risk of poor health and poor pregnancy outcomes (preeclampsia, preterm birth, gestational diabetes, etc.). In this work, we review the last decade of relevant research to improve our understanding of the mechanisms by which the microbiota of the female reproductive tract influences female reproductive health. This work discusses the mechanisms associated with the reproductive tract microbiota and pregnancy immunity, as well as the impact of an abnormal microbiota on adverse pregnancy outcomes. Emphasis is placed on the characteristics and sources of the female vaginal, uterine, and placental microbiota and the importance of a well-stabilized local human microbiota and immune system for embryo implantation, placental development, fetal growth, and pregnancy outcome.

Probiotics Properties: A Focus on Pregnancy Outcomes

A healthy microbiome plays an important role in the prevention of illness and maintenance of overall health, including reproductive health. Although the therapeutic advantages of probiotics have been shown to run across multiple organ systems, their role in pregnancy is not well explored. The aim of this review is to highlight the potential advantages and adverse effects of probiotics in pregnancy. Data were collected from the literature over the past decade using PubMed, Medline, Google Scholar, Ovid, Scopus, and Science Direct. A total of 40 articles were utilized in this review. Collected data indicated that prenatal and post-natal supplementation with lactobacilli alone or lactobacilli with Bifidobacterium spp. seems to be protective. Probiotics may improve insulin resistance and consequently reduce the risk of gestational diabetes. Probiotics may also reduce anxiety and depression by influencing brain activity. Additionally, they interfere with vaginal flora to make it friendlier to beneficial bacteria, and enhance anti-inflammatory or reduce pro-inflammatory cytokines. They may also decrease eczema in breastfed infants and prevent allergic reactions by downregulating Th2 responses to specific allergens from mid to late gestation. Leveraging the cervicovaginal microbiota could promote a number of positive pregnancy-related health outcomes. Caution should be exercised in the selection, dosing, and monitoring of probiotics administration. More comprehensive randomized clinical trials are needed to reach a more meaningful evidence-based clinical knowledge.

Dysbiosis in salivary bacterial diversity of postpartum females and its association with oral health problems and APOs

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In present study, salivary microbial diversity of postpartum females was compared with nonpregnant females.

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Microbial colonization was raised in postpartum females especially those having oral health issues.

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Isolated bacterial species showed enhanced biofilm forming and multi drug resistance.

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Alpha diversity was decrease in postpartum female having oral health issues with PLWB.

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Bray-Curtis dissimilarity was highest between females with dental issues and different pregnancy outcomes.

The present study investigates the dysbiosis in salivary bacterial diversity by culture-dependent and independent methods. Culturable aerobic and facultative anaerobic bacterial diversity was studied in saliva collected from 267 postpartum and 54 nonpregnant females by using standard microbiological methods. For unculturable bacterial diversity, DNA from saliva samples of four selected females was sequenced by targeting V4 region of 16S rRNA. In postpartum females, S. mutans was significantly more prevalent. Its colonization was also seen significant among females having gingivitis (P < 0.01), dental caries (P < 0.01), and in those giving birth to low weight baby. In postpartum group, 65.16% females were culture positive for Staphylococcus, 12.73% Gram positive rods, 10.48% N. meningitides, 6.36% K. pneumoniae, 5.61% Enterobacter species and 2.62% E. coli. Isolates showed high biofilm forming ability and antibiotic resistance. Upon analysis of unculturable bacterial diversity, a total of 16 phyla and 156 genera were observed. Alpha diversity was decrease in postpartum female having oral health issues with pre-term low weight birth, compared to females with full term birth. Bray-Curtis dissimilarity was highest between female with dental issues and different pregnancy outcomes. Bacterial diversity and abundance altered among females with different oral health conditions and pregnancy outcomes, and also have pathogenic potential.

Associations Between Dysmenorrhea Symptom-Based Phenotypes and Vaginal Microbiome: A Pilot Study

BACKGROUND

Dysmenorrhea is highly prevalent; it places women at risk for other chronic pain conditions. There is a high degree of individual variability in menstrual pain severity, the number of painful sites, and co-occurring gastrointestinal symptoms. Distinct dysmenorrhea symptom-based phenotypes were previously identified, but the biological underpinnings of these phenotypes are less known. One underexplored contributor is the vaginal microbiome. The vaginal microbiota differs significantly among reproductive-age women and may modulate as well as amplify reproductive tract inflammation, which may contribute to dysmenorrhea symptoms.

OBJECTIVES

The objective of this study was to examine associations between dysmenorrhea symptom-based phenotypes and vaginal microbiome compositions on- and off-menses.

METHODS

We conducted a prospective, longitudinal, pilot study of 20 women (aged 15-24 years) grouped into three dysmenorrhea symptom-based phenotypes: "mild localized pain," "severe localized pain," and "severe multiple pain and gastrointestinal symptoms." Over one menstrual cycle, participants provided vaginal swabs when they were on- and off-menses. We assayed the vaginal microbiome using 16S rRNA gene sequencing. Permutational multivariate analysis of variance tests were used to compare microbiome compositions across phenotypes, with heat maps generated to visualize the relative abundance of bacterial taxa.

RESULTS

The vaginal microbiome compositions (n = 40) were different across the three phenotypes. After separating the on-menses (n = 20) and off-menses (n = 20) specimens, the statistically significant difference was seen on-menses, but not off-menses. Compared to the "mild localized pain" phenotype, participants in the "multiple severe symptoms" phenotype had a lower lactobacilli level and a higher abundance of Prevotella, Atopobium, and Gardnerella when on-menses. We also observed trends of differences across phenotypes in vaginal microbiome change from off- to on-menses.

DISCUSSION

The study provides proof-of-concept data to support larger studies on associations between dysmenorrhea symptom-based phenotypes and vaginal microbiome that might lead to new intervention targets and/or biomarkers for dysmenorrhea. This line of research has the potential to inform precision dysmenorrhea treatment that can improve women's quality of life.

Cervicovaginal microbiome dynamics after taking oral probiotics

The vaginal microbiota is less complex than the gut microbiota, and the colonization of Lactobacillus in the female vagina is considered to be critical for reproductive health. Oral probiotics have been suggested as promising means to modulate vaginal homeostasis in the general population. In this study, 60 Chinese women were followed for over a year before, during, and after treatment with the probiotics Lactobacillus rhamnosus GR-1 and Lactobacillusreuteri RC-14. Shotgun metagenomic data of 1334 samples from multiple body sites did not support a colonization route of the probiotics from the oral cavity to the intestinal tract and then to the vagina. Our analyses enable the classification of the cervicovaginal microbiome into a stable state and a state of dysbiosis. The microbiome in the stable group steadily maintained a relatively high abundance of Lactobacilli over 1 year, which was not affected by probiotic intake, whereas in the dysbiosis group, the microbiota was more diverse and changed markedly over time. Data from a subset of the dysbiosis group suggests this subgroup possibly benefited from supplementation with the probiotics, indicating that probiotics supplementation can be prescribed for women in a subclinical microbiome setting of dysbiosis, providing opportunities for targeted and personalized microbiome reconstitution.

Plant Prebiotics and Their Role in the Amelioration of Diseases

Prebiotics are either natural or synthetic non-digestible (non-)carbohydrate substances that boost the proliferation of gut microbes. Undigested fructooligosaccharides in the large intestine are utilised by the beneficial microorganisms for the synthesis of short-chain fatty acids for their own growth. Although various food products are now recognized as having prebiotic properties, several others, such as almonds, artichoke, barley, chia seeds, chicory, dandelion greens, flaxseeds, garlic, and oats, are being explored and used as functional foods. Considering the benefits of these prebiotics in mineral absorption, metabolite production, gut microbiota modulation, and in various diseases such as diabetes, allergy, metabolic disorders, and necrotising enterocolitis, increasing attention has been focused on their applications in both food and pharmaceutical industries, although some of these food products are actually used as food supplements. This review aims to highlight the potential and need of these prebiotics in the diet and also discusses data related to the distinct types, sources, modes of action, and health benefits.

A specific bacterial DNA signature in the vagina of Australian women in midpregnancy predicts high risk of spontaneous preterm birth (the Predict1000 study)

BACKGROUND

Intrauterine infection accounts for a quarter of the cases of spontaneous preterm birth; however, at present, it is not possible to efficiently identify pregnant women at risk to deliver preventative treatments.

OBJECTIVE

This study aimed to establish a vaginal microbial DNA test for Australian women in midpregnancy that will identify those at increased risk of spontaneous preterm birth.

STUDY DESIGN

A total of 1000 women with singleton pregnancies were recruited in Perth, Australia. Midvaginal swabs were collected between 12 and 23 weeks' gestation. DNA was extracted for the detection of 23 risk-related microbial DNA targets by quantitative polymerase chain reaction. Obstetrical history, pregnancy outcome, and demographics were recorded.

RESULTS

After excluding 64 women owing to losses to follow-up and insufficient sample for microbial analyses, the final cohort consisted of 936 women of predominantly white race (74.3%). The overall preterm birth rate was 12.6% (118 births); the spontaneous preterm birth rate at <37 weeks' gestation was 6.2% (2.9% at ≤34 weeks' gestation), whereas the preterm premature rupture of the membranes rate was 4.2%. No single individual microbial target predicted increased spontaneous preterm birth risk. Conversely, women who subsequently delivered at term had higher amounts of Lactobacillus crispatus, Lactobacillus gasseri, or Lactobacillus jensenii DNA in their vaginal swabs (13.8% spontaneous preterm birth vs 31.2% term; P=.005). In the remaining women, a specific microbial DNA signature was identified that was strongly predictive of spontaneous preterm birth risk, consisting of DNA from Gardnerella vaginalis (clade 4), Lactobacillus iners, and Ureaplasma parvum (serovars 3 and 6). Risk prediction was improved if Fusobacterium nucleatum detection was included in the test algorithm. The final algorithm, which we called the Gardnerella Lactobacillus Ureaplasma (GLU) test, was able to detect women at risk of spontaneous preterm birth at <37 and ≤34 weeks' gestation, with sensitivities of 37.9% and 44.4%, respectively, and likelihood ratios (plus or minus) of 2.22 per 0.75 and 2.52 per 0.67, respectively. Preterm premature rupture of the membranes was more than twice as common in GLU-positive women. Adjusting for maternal demographics, ethnicity, and clinical history did not improve prediction. Only a history of spontaneous preterm birth was more effective at predicting spontaneous preterm birth than a GLU-positive result (odds ratio, 3.6).

CONCLUSION

We have identified a vaginal bacterial DNA signature that identifies women with a singleton pregnancy who are at increased risk of spontaneous preterm birth and may benefit from targeted antimicrobial therapy.

Defining microbial biomarkers for risk of preterm labor

Preterm birth remains the main contributor to early childhood mortality. The vaginal environment, including microbiota composition, might contribute to the risk of preterm delivery. Alterations in the vaginal microbial community structure might represent a risk factor for preterm birth. Here, we aimed to (a) investigate the association between preterm birth and the vaginal microbial community and (b) identify microbial biomarkers for risk of preterm birth. Microbial DNA was isolated from vaginal swabs in a cohort of 69 women enrolled at hospital admission for their delivery. Microbiota was analyzed by high-throughput 16S rRNA sequencing. While no differences in microbial diversity measures appeared associated with the spontaneous preterm and full-term outcomes, the microbial composition was distinct for these groups. Differential abundance analysis showed Lactobacillus species to be associated with full-term birth whereas an unknown Prevotella species was more abundant in the spontaneous preterm group. Although we studied a very miscegenated population from Brazil, our findings were similar to evidence pointed by other studies in different countries. The role of Lactobacillus species as a protector in the vaginal microbiome is demonstrated to be also a protector of spontaneous preterm outcome whereas the presence of pathogenic species, such as Prevotella spp., is endorsed as a factor of risk for spontaneous preterm delivery.

The Vaginal Microbiome in U.S. Black Women: A Systematic Review

Background: Advancements in next-generation sequencing have allowed for a more complete understanding of the vaginal microbiome and its role in health and disease. The role of race/ethnicity in the composition of the vaginal microbiome and what is deemed normal/healthy microbiome is conflicting. Thus, the purpose of this review is to synthesize research that investigated the vaginal microbiome in Black women in the United States by using advanced 16S analysis. Methods: Searches of Pubmed, Google Scholar, and relevant journals for publications between January 2008 and July 2018 were conducted. Eligibility criteria were that the study: (1) used a molecular technique for sequencing of the vaginal microbiome, (2) reported the microbiome by race/ethnicity that included Black women, and (3) was conducted in the United States. Results: Our review selected 18 manuscripts that met the inclusion criteria for full review. Three themes emerged: the vaginal microbiome in healthy women versus women with bacterial vaginosis (BV); vaginal microbiome considerations in HIV; and vaginal microbiome considerations in preterm labor/birth. Overall, our review found that a majority of Black women (including HIV-positive women) have a Lactobacillus dominant group. Specifically, Lactobacillus iners was the most frequently reported Lactobacillus species. Non-Lactobacillus dominant groups were also reported to be found in healthy asymptomatic Black women. The vaginal microbiome's influence on preterm labor and/or birth among Black women was inconclusive and warrants further investigation. Conclusions: The role that the microbiome plays in health and disease among Black women warrants further research to better elucidate the definition of a healthy versus pathogenic microbiome. The wide variability in methods for BV diagnostics and defining preterm labor/birth are significant limitations that should be considered when conducting comparative studies.

Mechanistic insights into the action of probiotics against bacterial vaginosis and its mediated preterm birth: An overview

The human body is a reservoir of numerous micro-creatures; whose role is substantial and indispensable in the overall development of human beings. The advances in omic approaches have offered powerful means to decipher the core microbiome and metabolome diversities in a specific organ system. The establishment of lactobacilli in the female reproductive tract is thought to be a paramount prerequisite that maintains homeostatic conditions for a sustainable and healthy pregnancy. Nevertheless, a plethora of such Lactobacillus strains of vaginal source revealed probiotic phenotypes. The plummeting in the occurrence of lactobacilli in the vaginal ecosystem is associated with several adverse pregnancy outcomes (APOs). One such pathological condition is "Bacterial Vaginosis" (BV), a pathogen dominated gynecological threat. In this scenario, the ascending traffic of notorious Gram-negative/variable BV pathogens to the uterus is one of the proposed pathways that give rise to inflammation-related APOs like preterm birth. Since antibiotic resistance is aggravating among urogenital pathogens, the probiotics intervention remains one of the alternative biotherapeutic strategies to overcome BV and its associated APOs. Perhaps, the increased inclination towards the safer and natural biotherapeutic strategies rather than pharmaceutical drugs for maintaining gestational and reproductive health resulted in the use of probiotics in pregnancy diets. In this context, the current review is an attempt to highlight the microbiome and metabolites signatures of BV and non-BV vaginal ecosystem, inflammation or infection-related preterm birth, host-microbial interactions, role and effectiveness of probiotics to fight against aforesaid diseased conditions.

Spontaneous preterm labour that leads to preterm birth: An update and personal reflection

OBJECTIVE

The objective was to provide an update of progress made over time (including personal reflection) of our attempts to reduce the mortality and morbidity associated with spontaneous preterm labour that leads to preterm birth.

METHODS

An experienced and evidence based approach was taken to provide an overview of progress made over a generation (∼40 years) in our understanding of spontaneous preterm labour.

RESULTS

It is evident that we have made significant progress in our understanding of the aetiology, the measurement of the burden, the basic science, systems biology and mechanical pathways of the preterm parturition syndrome. We have better ways of predicting, preventing and managing spontaneous preterm labour than existed a generation ago.

CONCLUSIONS

The profile of spontaneous preterm labour that leads to preterm birth, thanks to organisations such as the March of Dimes, WHO and PREBIC is much more evident than before. However, while we have come a long way, we must not be complacent, and clinicians and basic scientists must continue to work in harmony, while recruiting and encouraging young investigators to join the effort to improve survival and handicap in what is one of the Great Obstetric Syndromes.

Dominant inflammatory profile of the placenta in a preterm labor mouse model

Objective: Despite a growing association between inflammation and preterm labor, the underlying mechanisms explaining the development of preterm labor after infection are still poorly understood. Here, we use RNA-sequencing to characterize the transcriptome changes of placenta tissue in a preterm labor mouse model.Materials and methods: On day 15.5 of gestation, BALB/c mice received intrauterine injection of LPS to mimic preterm labor. A comprehensive catalog of genes was obtained using RNA-sequences and followed by bioinformatics analysis. The NOD-like receptor signaling pathway (Nod2, Cxcl1, Cxcl2, and IL-1β) and two downregulated genes (Ctsg and Snca) were selected for validating the results using qPCR analysis.Results: We identified 155 differentially expressed genes (DEGs), 84 biological processes and 45 pathways in the placenta using RNA-seq. Fifty-four biological processes could be categorized as immune-related processes and 33 pathways were mainly related to immune disease and infections. All genes were consistent between the RNA-seq and qPCR analyses.Conclusions: The dominant role for inflammatory biological processes and pathways in placenta can lead to preterm labor.

Through the Microbial Looking Glass: Premature Labor, Preeclampsia, and Gestational Diabetes: A Scoping Review

The influence of microbial factors on adverse perinatal outcomes has become the focal point of recent investigations, with particular interest in the role of the microbiome and probiotic interventions. The purpose of this scoping review was to identify and critique the most recent evidence about these factors as they relate to pregnancies complicated by preeclampsia (PEC), preterm birth (PTB), and gestational diabetes mellitus (GDM). Four databases (PubMed, EMBASE, Web of Science, and Cochrane) were searched for articles published in English in the last 10 years with the concepts of the microbiome, probiotics, and PEC, PTB, or GDM. Forty-nine articles were eligible for full-text review. Five articles were excluded, leaving 44 articles that met all the eligibility criteria. The relationships between the microbiome and the risk for PEC, PTB, and GDM are not fully elucidated, although probiotic interventions seem beneficial in decreasing PEC and GDM risk. Probiotic interventions targeting bacterial vaginosis and elimination of infection in women at risk for PTB appear to be beneficial. More research is needed to understand the contributions of the microbiome to adverse perinatal outcomes. Probiotic interventions appear to be effective in reducing risk for select outcomes.

Vaginal microbiome in early pregnancy and subsequent risk of spontaneous preterm birth: a case-control study

OBJECTIVES

To explore differences in the vaginal microbiome between preterm and term deliveries.

DESIGN

Nested case-control study in 3D cohort (design, develop, discover).

SETTING

Quebec, Canada.

SAMPLE

Ninety-four women with spontaneous preterm birth as cases [17 early (<34 weeks) and 77 late (34-36 weeks) preterm birth] and 356 women as controls with term delivery (≥37 weeks).

METHODS

To assess the vaginal microbiome by sequencing the V4 region of the 16S ribosomal RNA (rRNA) gene in swabs self-collected during early pregnancy.

MAIN OUTCOME MEASURES

Comparison of relative abundance of bacterial operational taxonomic units and oligotypes and identifying vaginal community state types (CSTs) in early or late spontaneous preterm and term deliveries.

RESULTS

Lactobacillus gasseri/ Lactobacillus johnsonii (coefficient -5.36, 95% CI -8.07 to -2.65), Lactobacillus crispatus (99%)/ Lactobacillus acidophilus (99%) (-4.58, 95% CI -6.20 to -2.96), Lactobacillus iners (99%)/ Ralstonia solanacearum (99%) (-3.98, 95% CI -6.48 to -1.47) and Bifidobacterium longum/ Bifidobacterium breve (-8.84, 95% CI -12.96 to -4.73) were associated with decreased risk of early but not late preterm birth. Six vaginal CSTs were identified: four dominated by Lactobacillus; one with presence of bacterial vaginosis-associated bacteria (Gardnerella vaginalis, Atopobium vaginae and Veillonellaceae bacterium) (CST IV); and one with nondominance of Lactobacillus (CST VI). CST IV was associated with increased risk of early (4.22, 95% CI 1.24-24.85) but not late (1.63, 95% CI 0.68-5.04) preterm birth, compared with CST VI.

CONCLUSIONS

Lactobacillus gasseri/L. johnsonii, L. crispatus/L. acidophilus, L. iners/R. solanacearum and B. longum/B. breve may be associated with decreased risk of early preterm birth. A bacterial vaginosis-related vaginal CST versus a CST nondominated by Lactobacillus may be associated with increased risk of early preterm birth.

TWEETABLE ABSTRACT

Largest study of its kind finds certain species of vaginal Lactobacillus + Bifidobacterium may relate to lower risk of preterm birth.

Clinical Relevance of Gastrointestinal Microbiota During Pregnancy: A Primer for Nurses

Emerging evidence about the human microbiome, a collective term for all the microorganisms living in and on the human body, consistently demonstrates the critical influence it has on host physiology and disease risk. The microbiota in the gastrointestinal (GI) tract has the most significant and far-reaching effect on human physiology. The maternal GI microbiota can decrease the risk of adverse pregnancy outcomes by modulating energy extraction, glucose metabolism, vitamin production, and host immunity essential for optimal maternal and neonatal health. Moreover, the maternal GI microbiota is thought to influence colonization of the fetus and neonate that may predispose them to different health trajectories. This article provides a basic understanding about the influence of the structure of the maternal GI microbiota, the fundamental role it plays during pregnancy, and the factors that influence the structure, and subsequently function, of the GI microbiota in the general and pregnant population. While only a small number of studies have examined this topic during pregnancy, the preponderance of the evidence supports the need to clarify baseline structure and function of GI microbiota and its associations with pregnancy outcomes. In addition, the results from the studies conducted in the general population can be extrapolated to pregnancy in many cases. This knowledge is essential for clinicians who need to understand the implications of the microbiota for disease and wellness in order to address the care factors that may adversely influence the GI microbiota during pregnancy.

Maternal microbiomes in preterm birth: Recent progress and analytical pipelines

Worldwide, 10% of babies are born preterm, defined as birth before 37 weeks' gestation. We have had little success in developing strategies to prevent preterm births, the majority of which are due to infection or are idiopathic. An emerging hypothesis is that the maternal microbiome-the bacteria that inhabit the mother's body and play vital functions in normal health-contributes to the etiology of preterm birth. Here, we highlight the latest data revealing correlations between preterm birth and maternal intestinal, vaginal, cervical, and placental microbiomes. Additionally, we describe the most commonly used comparative microbiome analysis methods and highlight important issues to consider when conducting such studies.

Yogurt consumption during pregnancy and preterm delivery in Mexican women: A prospective analysis of interaction with maternal overweight status

Preterm delivery is an important cause of perinatal morbidity and mortality, often precipitated by maternal infection or inflammation. Probiotic-containing foods, such as yogurt, may reduce systemic inflammatory responses. We sought to evaluate whether yogurt consumption during pregnancy is associated with decreased preterm delivery. We studied 965 women enrolled at midpregnancy into a clinical trial of prenatal docosahexaenoic acid supplementation in Mexico. Yogurt consumption during the previous 3 months was categorized as ≥5, 2-4, or <2 cups per week. Preterm delivery was defined as delivery of a live infant before 37 weeks gestation. We used logistic regression to evaluate the association between prenatal yogurt consumption and preterm delivery and examined interaction with maternal overweight status. In this population, 25.4%, 34.2%, and 40.4% of women reported consuming ≥5, 2-4, and <2 cups of yogurt per week, respectively. The prevalence of preterm delivery was 8.9%. Differences in preterm delivery were non-significant across maternal yogurt consumption groups; compared with women reporting <2 cups of yogurt per week, those reporting 2-4 cups of yogurt per week had adjusted odds ratio (aOR) for preterm delivery of 0.81 (95% confidence interval, CI [.46, 1.41]), and those reporting ≥5 cups of yogurt per week had aOR of 0.94 (95% CI [.51, 1.72]). The association between maternal yogurt consumption and preterm delivery differed significantly for nonoverweight women compared with overweight women (p for interaction = .01). Compared with nonoverweight women who consumed <2 cups of yogurt per week, nonoverweight women who consumed ≥5 cups of yogurt per week had aOR for preterm delivery of 0.24 (95% CI [.07, .89]). Among overweight women, there was no significant association. In this population, there was no overall association between prenatal yogurt consumption and preterm delivery. However, there was significant interaction with maternal overweight status; among nonoverweight women, higher prenatal yogurt consumption was associated with reduced preterm delivery.