Maternal influence on the fetal microbiome in a population-based study of the first-pass meconium

Pregnancy period and early-life risk factors for inflammatory bowel disease: a Northern Finland birth cohort 1966 study

BACKGROUND

The pathogenesis of inflammatory bowel disease (IBD) has not been fully elucidated. The aim of this study was to analyze the pregnancy period, perinatal period, and infancy period risk factors for IBD in a well-characterized birth cohort from Northern Finland.

METHODS

The Northern Finland Birth Cohort 1966 (NFBC1966) population comprises mothers living in the two northernmost provinces of Finland, Oulu, and Lapland, with dates of delivery between Jan 1st and Dec 31st, 1966 (12 055 mothers, 12 058 live-born children, 96.3% of all births during 1966). IBD patients were identified using hospital registries (from 1966 to 2020) and Social Insurance Institution (SII) registry reimbursement data for IBD drugs (from 1978 to 2016). The data were analyzed by Fisher's exact test and logistic regression.

RESULTS

In total, 6972 individuals provided informed consent for the use of combined SII and hospital registry data. Of those, 154 (2.1%) had IBD (113 [1.6%] had ulcerative colitis (UC), and 41 (0.6%) had Crohn's disease (CD)). According to multivariate analysis, maternal smoking > 10 cigarettes/day during pregnancy was associated with a nearly 6-fold increased risk of CD in the offspring (OR 5.78, 95% CI 1.70-17.3). Breastfeeding (OR = 0.18, 95% CI 0.08-0.44) and iron supplementation during the first year of life (OR = 0.43, 95% CI 0.21-0.89) were negatively associated with CD.

CONCLUSIONS

Smoking during pregnancy was associated with the risk of CD while Breastfeeding and oral iron supplementation at infancy were negatively associated with the risk of CD later in life.

Causal relationship between gut microbiota and rosacea: a two-sample Mendelian randomization study

Background

Rosacea, a chronic inflammatory skin condition affecting millions worldwide, is influenced by complex interactions between genetic and environmental factors. Although gut microbiota's role in skin health is well-acknowledged, definitive causal links between gut microbiota and rosacea remain under-explored.

Methods

Using a two-sample Mendelian randomization (MR) design, this study examined potential causal relationships between gut microbiota and rosacea. Data was sourced from the largest Genome-Wide Association Study (GWAS) for gut microbiota and the FinnGen biobank for rosacea. A total of 2078 single nucleotide polymorphisms (SNPs) associated with gut microbiota were identified and analyzed using a suite of MR techniques to discern causal effects.

Results

The study identified a protective role against rosacea for two bacterial genera: phylum Actinobacteria and genus Butyrivibrio. Furthermore, 14 gut microbiota taxa were discovered to exert significant causal effects on variant categories of rosacea. While none of these results met the strict False Discovery Rate correction threshold, they retained nominal significance. MR outcomes showed no pleiotropy, with homogeneity observed across selected SNPs. Directionality tests pointed toward a robust causative path from gut microbiota to rosacea.

Conclusion

This study provides compelling evidence of the gut microbiota's nominal causal influence on rosacea, shedding light on the gut-skin axis's intricacies and offering potential avenues for therapeutic interventions in rosacea management. Further research is warranted to validate these findings and explore their clinical implications.

Investigating prenatal and perinatal factors on meconium microbiota: a systematic review and cohort study

BACKGROUND

The first-pass meconium has been suggested as a proxy for the fetal gut microbiota because it is formed in utero. This systematic review and cohort study investigated how pre- and perinatal factors influence the composition of the meconium microbiota.

METHODS

We performed the systematic review using Covidence by searching PubMed, Scopus, and Web of Science databases with the search terms "meconium microbiome" and "meconium microbiota". In the cohort study, we performed 16 S rRNA gene sequencing on 393 meconium samples and analyzed the sequencing data using QIIME2.

RESULTS

Our systematic review identified 69 studies exploring prenatal factors, immediate perinatal factors, and microbial composition in relation to subsequent health of infants but gave only limited comparative evidence regarding factors related to the composition of the meconium microbiota. The cohort study pointed to a low-biomass microbiota consisting of the phyla Firmicutes, Proteobacteria and Actinobacteriota and the genera Staphylococcus, Escherichia-Shigella and Lactobacillus, and indicated that immediate perinatal factors affected the composition of the meconium microbiota more than did prenatal factors.

CONCLUSIONS

This finding supports the idea that the meconium microbiota mostly starts developing during delivery.

IMPACT

It is unclear when the first-pass meconium microbiota develops, and what are the sources of the colonization. In this systematic review, we found 69 studies exploring prenatal factors, immediate perinatal factors, and microbial composition relative to subsequent health of infants, but there was no consensus on the factors affecting the meconium microbiota development. In this cohort study, immediate perinatal factors markedly affected the meconium microbiota development while prenatal factors had little effect on it. As the meconium microbiota composition was influenced by immediate perinatal factors, the present study supports the idea that the initial gut microbiota develops mainly during delivery.

Impact of Maternal Mediterranean-Type Diet Adherence on Microbiota Composition and Epigenetic Programming of Offspring

Understanding how maternal diet affects in utero neonatal gut microbiota and epigenetic regulation may provide insight into disease origins and long-term health. The impact of Mediterranean diet pattern adherence (MDA) on fetal gut microbiome and epigenetic regulation was assessed in 33 pregnant women. Participants completed a validated food frequency questionnaire in each trimester of pregnancy; the alternate Mediterranean diet (aMED) score was applied. Umbilical cord blood, placental tissue, and neonatal meconium were collected from offspring. DNA methylation patterns were probed using the Illumnia EPICarray Methylation Chip in parturients with high versus low MDA. Meconium microbial abundance in the first 24 h after birth was identified using 16s rRNA sequencing and compared among neonates born to mothers with high and low aMED scores. Twenty-one mothers were classified as low MDA and 12 as high MDA. Pasteurellaceae and Bacteroidaceae trended towards greater abundance in the high-MDA group, as well as other short-chain fatty acid-producing species. Several differentially methylated regions varied between groups and overlapped gene regions including NCK2, SNED1, MTERF4, TNXB, HLA-DPB, BAG6, and LMO3. We identified a beneficial effect of adherence to a Mediterranean diet on fetal in utero development. This highlights the importance of dietary counseling for mothers and can be used as a guide for future studies of meconium and immuno-epigenetic modulation.

The Importance of a Healthy Microbiome in Pregnancy and Infancy and Microbiota Treatment to Reverse Dysbiosis for Improved Health

BACKGROUND

The microbiome of newborn infants during the first 1000 days, influenced early on by their mothers' microbiome health, mode of delivery and breast feeding, orchestrates the education and programming of the infant's immune system and determines in large part the general health of the infant for years.

METHODS

PubMed was reviewed for maternal infant microbiome health and microbiota therapy in this setting with prebiotics, probiotics, vaginal seeding and fecal microbiota transplantation (FMT).

RESULTS

A healthy nonobese mother, vaginal delivery and strict breast feeding contribute to microbiome health in a newborn and young infant. With reduced microbiome diversity (dysbiosis) during pregnancy, cesarean delivery, prematurity, and formula feeding contribute to dysbiosis in the newborn. Microbiota therapy is an important approach to repair dysbiosis in pregnant women and their infants. Currently available probiotics can have favorable metabolic effects on mothers and infants, but these effects are variable. In research settings, reversal of infant dysbiosis can be achieved via vaginal seeding or FMT. Next generation probiotics in development should replace current probiotics and FMT.

CONCLUSIONS

The most critical phase of human microbiome development is in the first 2-3 years of life. Preventing and treating dysbiosis during pregnancy and early life can have a profound effect on an infant's later health.

Infant gut microbiota colonization: influence of prenatal and postnatal factors, focusing on diet

Maternal microbiota forms the first infant gut microbial inoculum, and perinatal factors (diet and use of antibiotics during pregnancy) and/or neonatal factors, like intra partum antibiotics, gestational age and mode of delivery, may influence microbial colonization. After birth, when the principal colonization occurs, the microbial diversity increases and converges toward a stable adult-like microbiota by the end of the first 3-5 years of life. However, during the early life, gut microbiota can be disrupted by other postnatal factors like mode of infant feeding, antibiotic usage, and various environmental factors generating a state of dysbiosis. Gut dysbiosis have been reported to increase the risk of necrotizing enterocolitis and some chronic diseases later in life, such as obesity, diabetes, cancer, allergies, and asthma. Therefore, understanding the impact of a correct maternal-to-infant microbial transfer and a good infant early colonization and maturation throughout life would reduce the risk of disease in early and late life. This paper reviews the published evidence on early-life gut microbiota development, as well as the different factors influencing its evolution before, at, and after birth, focusing on diet and nutrition during pregnancy and in the first months of life.

Compositional and functional variability of the gut microbiome in children with infantile colic

The inconsolable crying of a child for no apparent reason at an early age is a source of excitement and anxiety for parents. Previous studies have reported that crying may be caused by discomfort associated with the occupation of the intestines of the newborn by microbiota and its vital activity. We conducted a prospective observational study in which 62 newborns and their mothers were recruited. The study comprised two groups, each consisting of 15 infants with colic and 21 controls. Colic and control groups were vaginally born and exclusively breastfed. Fecal samples from children were collected over time from day 1 to 12 months. Full metagenomic sequencing of fecal samples from children and their mothers was carried out. It was determined that the trajectory of the development of the intestinal microbiome of children with colic was different from the group without colic. In the colic group, a depleted relative abundance of Bifidobacterium and enrichment of Bacteroides Clostridiales was found, while the microbial biodiversity in this group was enriched. Metabolic pathway profiling showed that the non-colic group was enriched by amino acid biosynthetic pathways, while the feces microbiome of the colic group was enriched by glycolysis metabolic pathways that correlated with the Bacteroides taxon. This study shows that infantile colic has a definite relationship with the microbiome structure of infants.

Bacterial extracellular vesicles in the microbiome of first-pass meconium in newborn infants

BACKGROUND

Bacterial extracellular vesicles (EVs) are more likely to cross biological barriers than whole-cell bacteria. We previously observed EV-sized particles by electron microscopy in the first-pass meconium of newborn infants. We hypothesized that EVs may be of bacterial origin and represent a novel entity in the human microbiome during fetal and perinatal periods.

METHODS

We extracted EVs from first-pass meconium samples of 17 newborn infants and performed bacterial 16S rRNA gene sequencing of the vesicles. We compared the EV content from the meconium samples of infants based on the delivery mode, and in vaginal delivery samples, based on the usage of intrapartum antibiotics.

RESULTS

We found bacterial EVs in all first-pass meconium samples. All EV samples had bacterial RNA. Most of the phyla present in the samples were Firmicutes (62%), Actinobacteriota (18%), Proteobacteria (10%), and Bacteroidota (7.3%). The most abundant genera were Streptococcus (21%) and Staphylococcus (17%). The differences between the delivery mode and exposure to antibiotics were not statistically significant.

CONCLUSIONS

Bacterial EVs were present in the first-pass meconium of newborn infants. Bacterial EVs may represent an important novel feature of the gut microbiome during fetal and perinatal periods.

IMPACT

We show that bacterial extracellular vesicles are present in the microbiome of first-pass meconium in newborn infants. This is a novel finding. To our knowledge, this is the first study to report the presence of bacterial extracellular vesicles in the gut microbiome during fetal and perinatal periods. This finding is important because bacterial extracellular vesicles are more likely to cross biological barriers than whole-cell bacteria. Thus, the early gut microbiome may potentially interact with the host through bacterial EVs.

Comparative Analyses of the Gut Microbiota in Growing Ragdoll Cats and Felinae Cats

Simple Summary

Accumulating studies have revealed that the gut microbiota had intimate relations with the animal gastrointestinal tract diseases. Through regulating the development of the host’s intestinal immune system, the gut microbiota could directly influence the host’s intestinal function. In the current study, the gut microbiota of Ragdoll cats and Felinae cats were investigated and compared. Results demonstrated the diversity and richness of the gut microbiota in the Felinae cats were much higher than in the Ragdoll cats. However, the relative abundances of beneficial microbes in the Ragdoll cats were much higher than those in the Felinae cats. In all, different genetic portraits determined the different microbial communities in the feline gut. The candidate probiotics isolated in the growing cat’s gut might be applied to treat the gastrointestinal tract diseases.

Abstract

Today, domestic cats are important human companion animals for their appearance and favorable personalities. During the history of their domestication, the morphological and genetic portraits of domestic cats changed significantly from their wild ancestors, and the gut microbial communities of different breeds of cats also apparently differ. In the current study, the gut microbiota of Ragdoll cats and Felinae cats were analyzed and compared. Our data indicated that the diversity and richness of the gut microbiota in the Felinae cats were much higher than in the Ragdoll cats. The taxonomic analyses revealed that the most predominant phyla of the feline gut microbiota were Firmicutes, Bacteroidota, Fusobacteriota, Proteobacteria, Actinobacteriota, Campilobacterota, and others, while the most predominant genera were Anaerococcus, Fusobacterium, Bacteroides, Escherichia-Shigella, Finegoldia, Porphyromonas, Collinsella, Lactobacillus, Ruminococcus_gnavus_group, Prevotella, and others. Different microbial communities between the Ragdoll group and the Felinae group were observed, and the compared results demonstrated that the relative abundances of beneficial microbes (such as Lactobacillus, Enterococcus, Streptococcus, Blautia, Roseburia, and so on) in the Ragdoll group were much higher than in the Felinae group. The co-occurrence network revealed that the number of nodes and links in the Felinae group was significantly higher than the Ragdoll group, which meant that the network of the Felinae group was larger and more complex than that of the Ragdoll group. PICRUSt function analyses indicated that the differences in microbial genes might influence the energy metabolism and immune functions of the host. In all, our data demonstrated that the richness and diversity of beneficial microbes in the Ragdoll group were much higher than the Felinae group. Therefore, it is possible to isolate and identify more candidate probiotics in the gut microbiota of growing Ragdoll cats.

The Effects of Probiotics, Prebiotics and Synbiotics in Non-Alcoholic Fat Liver Disease (NAFLD) and Non-Alcoholic Steatohepatitis (NASH): A Systematic Review

Modifications in the microbiota caused by environmental and genetic reasons can unbalance the intestinal homeostasis, deregulating the host’s metabolism and immune system, intensifying the risk factors for the development and aggravation of non-alcoholic fat liver disease (NAFLD). The use of probiotics, prebiotics and synbiotics have been considered a potential and promising strategy to regulate the gut microbiota and produce beneficial effects in patients with liver conditions. For this reason, this review aimed to evaluate the effectiveness of probiotics, prebiotics, and symbiotics in patients with NAFLD and NASH. Pubmed, Embase, and Cochrane databases were consulted, and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines were followed. The clinical trials used in this study demonstrated that gut microbiota interventions could improve a wide range of markers of inflammation, glycemia, insulin resistance, dyslipidemia, obesity, liver injury (decrease of hepatic enzymes and steatosis and fibrosis). Although microbiota modulators do not play a healing role, they can work as an important adjunct therapy in pathological processes involving NAFLD and its spectrums, either by improving the intestinal barrier or by preventing the formation of toxic metabolites for the liver or by acting on the immune system.

Impact of intrapartum antibiotics on the infant gastrointestinal microbiome: a narrative review

BACKGROUND

The composition of the infant gastrointestinal (GI) microbiome has been linked to adverse long-term health outcomes and neonatal sepsis. Several factors are known to impact the composition of the microbiome, including mode of delivery, gestational age, feeding method and exposure to antibiotics. The impact of intrapartum antibiotics (IPAs) on the infant microbiome requires further research.

OBJECTIVE

We aimed to evaluate the impact of IPAs on the infant GI microbiome.

METHODS

We searched Ovid MEDLINE and Embase Classic+Embase for articles in English reporting on the microbiome of infants exposed to IPAs from the date of inception to 3 January 2021. Primary outcomes included abundance and colonisation of Bifidobacterium and Lactobacillus, as well as alpha and beta diversity.

RESULTS

30 papers were included in this review. In the first year of life, following exposure to IPAs, 30% (6/20) of infant cohorts displayed significantly reduced Bifidobacterium, 89% (17/19) did not display any significant differences in Lactobacillus colonisation, 21% (7/34) displayed significantly reduced alpha diversity and 35% (12/34) displayed alterations in beta diversity. Results were further stratified by delivery, gestational age (preterm or full term) and feeding method.

CONCLUSIONS

IPAs impact the composition of the infant GI microbiome, resulting in possible reductions Bifidobacterium and alpha diversity, and possible alterations in beta diversity. Our findings may have implications for maternal and neonatal health, including interventions to prevent reductions in health-promoting bacteria (eg, probiotics) and IPA class selection.

Microbiota of the first-pass meconium and subsequent atopic and allergic disorders in children

BACKGROUND

Some cohort studies have suggested that gut microbiota composition is associated with allergic diseases in children. The microbiota of the first-pass meconium, which forms before birth, represents the first gut microbiota that is easily available for research and little is known about any relationship with allergic disease development.

OBJECTIVE

We investigated whether the bacterial composition of the first-pass meconium is associated with the development of allergic diseases before 4 years of age.

METHODS

Prospective birth cohort study. Bacterial composition of first-pass meconium was analysed using bacterial 16S rRNA gene amplicon sequencing. Atopic and allergic diseases were evaluated via online survey or telephone to age 4 years, based on the International Study of Asthma and Allergies in Childhood questionnaire.

RESULTS

During a 6-week period in 2014, 312 children were born at the Central Finland Central Hospital. Meconium was collected from 212 at a mean of 8-hour age. Outcome data at 4 years were available for 177 (83%) children, and 159 of these had sufficient amplification of bacterial DNA in meconium. Meconium microbiota composition, including diversity indices and relative abundances of the main phyla and genera, was not associated with subsequent atopic eczema, wheezing or cow's milk allergy. Principal components analysis did not identify any clustering of the meconium microbiomes of children with respect to wheezing or cow's milk allergy.

CONCLUSIONS

We found no evidence that gut microbiota composition of first-pass meconium is associated with atopic manifestations to age 4 years. However, larger studies are needed to fully exclude a relationship.

Gardnerella vaginalis in Recurrent Urinary Tract Infection Is Associated with Dysbiosis of the Bladder Microbiome

Recent studies on the urine microbiome have highlighted the importance of the gut–vagina–bladder axis in recurrent urinary tract infection (rUTI). In particular, the role of Gardnerella as a covert pathogen that activates E. coli in animal experiments has been reported. Herein, we conducted a human bladder microbiome study to investigate the effect of Gardnerella on rUTI. Urine 16S ribosomal RNA gene sequencing via transurethral catheterization was conducted in the normal control group (NC) (n = 18) and rUTI group (n = 78). The positive detection rate of Gardnerella species did not differ between the NC and rUTI groups (22.2% vs. 18.0%, p = 0.677). In addition, the Gardnerella-positive NC and Gardnerella-positive rUTI groups showed similar levels of microbiome diversity. The Gardnerella-positive group was categorized into three subgroups: the Escherichia-dominant group, Gardnerella-dominant group, and Lactobacillus-dominant group. All of the Escherichia-dominant groups were associated with rUTI. The Gardnerella-dominant or Lactobacillus-dominant groups expressed rUTI with symptoms when risk factors such as the degree of Gardnerella proliferation or causative agents of bacterial vaginosis were present. The presence of Gardnerella in the urine is considered to be related to rUTI depending on other risk factors. New guideline recommendations regarding antibiotic selection based on a novel method to detect the cause of rUTI may be required to reduce antibiotic resistance.

Gut microbiota in gastrointestinal diseases during pregnancy

Gut microbiota (GM) is a micro-ecosystem composed of all microorganisms in the human intestine. The interaction between GM and the host plays an important role in maintaining normal physiological functions in the host. Dysbiosis of the GM may cause various diseases. GM has been demonstrated to be associated with human health and disease, and changes during individual development and disease. Pregnancy is a complicated physiological process. Hormones, the immune system, metabolism, and GM undergo drastic changes during pregnancy. Gastrointestinal diseases during pregnancy, such as hepatitis, intrahepatic cholestasis of pregnancy, and pre-eclampsia, can affect both maternal and fetal health. The dysregulation of GM during pregnancy may lead to a variety of diseases, including gastrointestinal diseases. Herein, we review recent research articles on GM in pregnancy-related gastrointestinal diseases, discuss the interaction of the GM with the host under normal physiological conditions, gastrointestinal diseases, and pregnancy-specific disorders. As more attention is paid to reproductive health, the pathogenic mechanism of GM in gastrointestinal diseases during pregnancy will be further studied to provide a theoretical basis for the use of probiotics to treat these diseases.

Maternal and early life exposures and their potential to influence development of the microbiome

At the dawn of the twentieth century, the medical care of mothers and children was largely relegated to family members and informally trained birth attendants. As the industrial era progressed, early and key public health observations among women and children linked the persistence of adverse health outcomes to poverty and poor nutrition. In the time hence, numerous studies connecting genetics ("nature") to public health and epidemiologic data on the role of the environment ("nurture") have yielded insights into the importance of early life exposures in relation to the occurrence of common diseases, such as diabetes, allergic and atopic disease, cardiovascular disease, and obesity. As a result of these parallel efforts in science, medicine, and public health, the developing brain, immune system, and metabolic physiology are now recognized as being particularly vulnerable to poor nutrition and stressful environments from the start of pregnancy to 3 years of age. In particular, compelling evidence arising from a diverse array of studies across mammalian lineages suggest that modifications to our metagenome and/or microbiome occur following certain environmental exposures during pregnancy and lactation, which in turn render risk of childhood and adult diseases. In this review, we will consider the evidence suggesting that development of the offspring microbiome may be vulnerable to maternal exposures, including an analysis of the data regarding the presence or absence of a low-biomass intrauterine microbiome.

Impact of gut microbiome on skin health: gut-skin axis observed through the lenses of therapeutics and skin diseases

The human intestine hosts diverse microbial communities that play a significant role in maintaining gut-skin homeostasis. When the relationship between gut microbiome and the immune system is impaired, subsequent effects can be triggered on the skin, potentially promoting the development of skin diseases. The mechanisms through which the gut microbiome affects skin health are still unclear. Enhancing our understanding on the connection between skin and gut microbiome is needed to find novel ways to treat human skin disorders. In this review, we systematically evaluate current data regarding microbial ecology of healthy skin and gut, diet, pre- and probiotics, and antibiotics, on gut microbiome and their effects on skin health. We discuss potential mechanisms of the gut-skin axis and the link between the gut and skin-associated diseases, such as psoriasis, atopic dermatitis, acne vulgaris, rosacea, alopecia areata, and hidradenitis suppurativa. This review will increase our understanding of the impacts of gut microbiome on skin conditions to aid in finding new medications for skin-associated diseases.

Freeze-Thaw Pretreatment Can Improve Efficiency of Bacterial DNA Extraction From Meconium

Although the presence of live microbes in utero remains under debate, newborn gastrointestinal bacteria are undoubtedly important to infant health. Measuring bacteria in meconium is an ideal strategy to understand this issue; however, the low efficiency of bacterial DNA extraction from meconium has limited its utilization. This study aims to improve the efficiency of bacterial DNA extraction from meconium, which generally has low levels of microflora but high levels of PCR inhibitors in the viscous matrix. The research was approved by the ethical committee of the Xiamen Maternity and Child Health Care Hospital, Xiamen, China. All the mothers delivered naturally, and their newborns were healthy. Meconium samples passed by the newborns within 24 h were collected. Each sample was scraped off of a sterile diaper, transferred to a 5-ml sterile tube, and stored at −80°C. For the assay, a freeze-thawing sample preparation protocol was designed, in which a meconium-InhibitEX buffer mixture was intentionally frozen 1–3 times at −20°C, −80°C, and (or) in liquid nitrogen. Then, DNA was extracted using a commercial kit and sequenced by 16S rDNA to verify the enhanced bacterial DNA extraction efficiency. Ultimately, we observed the following: (1) About 30 mg lyophilized meconium was the optimal amount for DNA extraction. (2) Freezing treatment for 6 h improved DNA extraction at −20°C. (3) DNA extraction efficiency was significantly higher with the immediate thaw strategy than with gradient thawing at −20°C, −80°C, and in liquid nitrogen. (4) Among the conditions of −20°C, −80°C, and liquid nitrogen, −20°C was the best freezing condition for both improving DNA extraction efficiency and preserving microbial species diversity in meconium, while liquid nitrogen was the worst condition. (5) Three freeze-thaw cycles could markedly enhance DNA extraction efficiency and preserve the species diversity of meconium microflora. We developed a feasible freeze-thaw pretreatment protocol to improve the extraction of microbial DNA from meconium, which may be beneficial for newborn bacterial colonization studies.

Exposure to Meconium-Stained Amniotic Fluid and Long-Term Neurological-Related Hospitalizations throughout Childhood

OBJECTIVE

This study aimed to investigate the possible impact of meconium-stained amniotic fluid (MSAF) on the occurrence of neurological-related hospitalizations throughout childhood and adolescence.

STUDY DESIGN

In this population-based cohort analysis, all singleton deliveries occurring between 1991 and 2014 at the Soroka University Medical center were included and the long-term neurological-related hospitalizations were compared between children with and without MSAF during their delivery. A Kaplan-Meier survival analysis was constructed for the evaluation of cumulative hospitalization rate due to neurological morbidity over the 18 years of follow-up, and a Cox proportional hazards model was used to study the independent association between MSAF and childhood neurological morbidity while controlling for potential confounders.

RESULTS

During the study period, 243,725 deliveries met the inclusion criteria; 35,897 of the cohort (15%) constituted the exposed group (MSAF), while the rest of the cohort (n = 207,828) constituted the unexposed group (no MSAF). A total of 7,543 hospitalizations due to neurological-related morbidity were documented with a rate of 3.2% (1,152) in children exposed to MSAF as compared with 3.1% (6,391) in the unexposed group (OR 1.1, 95% confidence interval 0.9-1.1, p = 0.149). The survival curve showed a comparable cumulative hospitalization rate in the MSAF-exposed group compared with the unexposed group (log rank p = 0.349). The Cox analysis, controlled for gestational diabetes and hypertension, gestational and maternal ages, demonstrated MSAF exposure not to be an independent risk factor for neurological-related hospitalizations during childhood (adjusted hazard ratio = 1.03, 0.96-1.09).

CONCLUSION

Fetal exposure to MSAF, at any gestational age, does not appear to be an independent risk factor for later neurological-related hospitalizations throughout childhood and adolescence.

KEY POINTS

· MSAF is associated with several short-term complications such as low Apgar scores.. · The long-term implications of MSAF exposure are yet to be clearly defined.. · Fetal exposure to MSAF is not a risk factor for neurological morbidity throughout childhood..

Early development of the skin microbiome: therapeutic opportunities

As human skin hosts a diverse microbiota in health and disease, there is an emerging consensus that dysregulated interactions between host and microbiome may contribute to chronic inflammatory disease of the skin. Neonatal skin is a unique habitat, structurally similar to the adult but with a different profile of metabolic substrates, environmental stressors, and immune activity. The surface is colonized within moments of birth with a bias toward maternal strains. Initial colonists are outcompeted as environmental exposures increase and host skin matures. Nonetheless, early life microbial acquisitions may have long-lasting effects on health through modulation of host immunity and competitive interactions between bacteria. Microbial ecology and its influence on health have been of interest to dermatologists for >50 years, and an explosion of recent interest in the microbiome has prompted ongoing investigations of several microbial therapeutics for dermatological disease. In this review, we consider how recent insight into the host and microbial factors driving development of the skin microbiome in early life offers new opportunities for therapeutic intervention. IMPACT: Advancement in understanding molecular mechanisms of bacterial competition opens new avenues of investigation into dermatological disease. Primary development of the skin microbiome is determined by immunological features of the cutaneous habitat. Understanding coordinated microbial and immunological development in the pediatric patient requires a multidisciplinary synthesis of primary literature.

Presence of distinctive microbiome in the first-pass meconium of newborn infants

We critically evaluated the fetal microbiome concept in 44 neonates with placenta, amniotic fluid, and first-pass meconium samples. Placental histology showed no signs of inflammation. Meconium samples were more often bacterial culture positive after vaginal delivery. In next-generation sequencing of the bacterial 16S gene, before and after removal of extracellular and PCR contaminant DNA, the median number of reads was low in placenta (48) and amniotic fluid (46) and high in meconium samples (14,556 C-section, 24,860 vaginal). In electron microscopy, meconium samples showed extracellular vesicles. Utilizing the analysis of composition of microbiomes (ANCOM) against water, meconium samples had a higher relative abundance of Firmicutes, Lactobacillus, Streptococcus, and Escherichia-Shigella. Our results did not support the existence of the placenta and amniotic fluid microbiota in healthy pregnancies. The first-pass meconium samples, formed in utero, appeared to harbor a microbiome that may be explained by perinatal colonization or intrauterine colonization via bacterial extracellular vesicles.

Delivery mode and perinatal antibiotics influence the predicted metabolic pathways of the gut microbiome

Delivery mode and perinatal antibiotics influence gut microbiome composition in children. Most microbiome studies have used the sequencing of the bacterial 16S marker gene but have not reported the metabolic function of the gut microbiome, which may mediate biological effects on the host. Here, we used the PICRUSt2 bioinformatics tool to predict the functional profiles of the gut microbiome based on 16S sequencing in two child cohorts. Both Caesarean section and perinatal antibiotics markedly influenced the functional profiles of the gut microbiome at the age of 1 year. In machine learning analysis, bacterial fatty acid, phospholipid, and biotin biosynthesis were the most important pathways that differed according to delivery mode. Proteinogenic amino acid biosynthesis, carbohydrate degradation, pyrimidine deoxyribonucleotide and biotin biosynthesis were the most important pathways differing according to antibiotic exposure. Our study shows that both Caesarean section and perinatal antibiotics markedly influence the predicted metabolic profiles of the gut microbiome at the age of 1 year.

The maternal gut microbiome during pregnancy and offspring allergy and asthma

Environmental exposures during pregnancy that alter both the maternal gut microbiome and the infant's risk of allergic disease and asthma include a traditional farm environment and consumption of unpasteurized cow's milk, antibiotic use, dietary fiber and psychosocial stress. Multiple mechanisms acting in concert may underpin these associations and prime the infant to acquire immune competence and homeostasis following exposure to the extrauterine environment. Cellular and metabolic products of the maternal gut microbiome can promote the expression of microbial pattern recognition receptors, as well as thymic and bone marrow hematopoiesis relevant to regulatory immunity. At birth, transmission of maternally derived bacteria likely leverages this in utero programming to accelerate postnatal transition from a Th2 to Th1 and Th17 dominant immune phenotypes and maturation of regulatory immune mechanisms, which in turn reduce the child's risk of allergic disease and asthma. Although our understanding of these phenomena is rapidly evolving, the field is relatively nascent, and we are yet to translate existing knowledge into interventions that substantially reduce disease risk in humans. Here we review evidence that the maternal gut microbiome impacts the offspring's risk of allergic disease and asthma, discuss challenges and future directions for the field, and propose the hypothesis that maternal carriage of Prevotella copri during pregnancy decreases the offspring's risk of allergic disease via production of succinate which in turn promotes bone marrow myelopoiesis of dendritic cell precursors in the fetus.

A Review of the Brain-Gut-Microbiome Axis and the Potential Role of Microbiota in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative process characterized by loss of neurons in the hippocampus and cerebral cortex, leading to progressive cognitive decline. Pathologically, the hallmark of AD is accumulation of "senile" plaques composed of amyloid-β (Aβ) protein surrounding neurons in affected regions. Despite extensive research into AD pathogenesis and therapeutic targets, there remains no breakthroughs in its management. In recent years, there has been a spark of interest in the connection between the brain and gastrointestinal tract, referred to as the brain-gut axis, and its potential implications for both metabolic and neurologic disease. Moreover, the gastrointestinal flora, referred to as the microbiome, appears to exert significant influence over the brain-gut axis. With the need for expanded horizons in understanding and treating AD, many have turned to the brain-gut-microbiome axis for answers. Here we provide a review of the brain-gut-microbiome axis and discuss the evidence supporting alterations of the axis in the pathogenesis of AD. Specifically, we highlight the role for the microbiome in disruption of Aβ metabolism/clearance, increased permeability of the blood-brain barrier and modulation of the neuroinflammatory response, and inhibition of hippocampal neurogenesis. The majority of the above described findings are the result of excellent, albeit basic and pre-clinical studies. Therefore, we conclude with a brief description of documented clinical support for brain-gut-microbiome axis alteration in AD, including potential microbiome-based therapeutics for AD. Collectively, these findings suggest that the brain-gut-microbiome axis may be a "lost link" in understanding and treating AD and call for future work.

Changes in the Distribution of Intrauterine Microbiota May Attribute to Immune Imbalance in the CBA/J×DBA/2 Abortion-Prone Mice Model

Background: Female Genital Tract (FGT) is an important micro-ecological area of human body. Microbiota in the lower reproductive tract may subsequently invade the uterine cavity during embryo implantation and produce immune responses. CBA/J×DBA/2 mating combination has been widely used as an abortion-prone mice model but whether microbiota existed in their uterine cavity remains unclear. In this context, the role of the microbial communities in immune response deserves attention.

Objective: To investigate the relationship between the distribution of microbiota in the uterine cavity of CBA/J×DBA/2 abortion-prone mouse model and the immune imbalance of the maternal-fetal interface.

Methods: In this study, female CBA/J mice were paired with male DBA/2 mice to develop an abortion-prone model (BA group), and with male BALB/c mice to build a standard pregnancy model (BC group). The non-pregnant female mice were served as the control group (C group). Uterine flushing fluid and sera were collected on day 13.5 of pregnancy. 16S rRNA sequencing technology was used to analyze the distribution of intrauterine microbiota. Phylogenetic Investigation of Communities were conducted to predict the microbiota functions by Reconstruction of Unobserved States (PICRUST) and Kyoto Encyclopedia of Genes and Genomes (KEGG). The serum IL 10, INF-γ, and TNF-α levels were examined using Enzyme-linked immunosorbent assay (ELISA) method.

Results: All samples were detected with microbial communities. The α diversity (p = 0.00077) had significant differences among three groups. Proteobacteria was the most dominant phylum in C group (mean = 83.21%) and BA group (mean = 43.23%). Firmicutes was dominant in BC group (mean = 46.4%), as well as the second dominant one in C group (mean = 12.63%) and BA group (mean = 40.55%). Microbiota functions were associated with metabolism and immune response through the NOD-like receptor signaling pathway. The serum IL 10 level in BA group were significantly lower than that in BC group (10.14 ± 1.90 pg/ml, n = 8; vs. 19.03 ± 1.82 pg/ml, n = 10; p = 0.004). The serum TNF-α and INF-γ level in BA group were also significantly higher than that in BC group (523.1 ± 58.14 pg/ml, n = 8 vs. 310.3 ± 28.51 pg/ml, n = 10, p = 0.0029; 69.22 ± 5.38 pg/ml, n = 8 vs. 50.85 ± 2.45 pg/ml, n = 10, p = 0.0042).

Conclusion: Microbial communities were colonized in uterine cavity of CBA/J mice both at non-pregnant stage and pregnant stage when mated with both BALB/c and DBA/2 male mice. The differentially abundant microbiome may be attributed to the immune tolerance through binding to the NOD-like receptor.

When a Neonate Is Born, So Is a Microbiota

In recent years, the role of human microbiota as a short- and long-term health promoter and modulator has been affirmed and progressively strengthened. In the course of one’s life, each subject is colonized by a great number of bacteria, which constitute its specific and individual microbiota. Human bacterial colonization starts during fetal life, in opposition to the previous paradigm of the “sterile womb”. Placenta, amniotic fluid, cord blood and fetal tissues each have their own specific microbiota, influenced by maternal health and habits and having a decisive influence on pregnancy outcome and offspring outcome. The maternal microbiota, especially that colonizing the genital system, starts to influence the outcome of pregnancy already before conception, modulating fertility and the success rate of fertilization, even in the case of assisted reproduction techniques. During the perinatal period, neonatal microbiota seems influenced by delivery mode, drug administration and many other conditions. Special attention must be reserved for early neonatal nutrition, because breastfeeding allows the transmission of a specific and unique lactobiome able to modulate and positively affect the neonatal gut microbiota. Our narrative review aims to investigate the currently identified pre- and peri-natal factors influencing neonatal microbiota, before conception, during pregnancy, pre- and post-delivery, since the early microbiota influences the whole life of each subject.

Gut microbiota and aging

Aging is characterized by the functional decline of tissues and organs and increased risk of aging-associated disorders, which pose major societal challenges and are a public health priority. Despite extensive human genetics studies, limited progress has been made linking genetics with aging. There is a growing realization that the altered assembly, structure and dynamics of the gut microbiota actively participate in the aging process. Age-related microbial dysbiosis is involved in reshaping immune responses during aging, which manifest as immunosenescence (insufficiency) and inflammaging (over-reaction) that accompany many age-associated enteric and extraenteric diseases. The gut microbiota can be regulated, suggesting a potential target for aging interventions. This review summarizes recent findings on the physiological succession of gut microbiota across the life-cycle, the roles and mechanisms of gut microbiota in healthy aging, alterations of gut microbiota and aging-associated diseases, and the gut microbiota-targeted anti-aging strategies.

Role of the Intestinal Epithelium and Its Interaction With the Microbiota in Food Allergy

The intestinal epithelial tract forms a dynamic lining of the digestive system consisting of a range of epithelial cell sub-types with diverse functions fulfilling specific niches. The intestinal epithelium is more than just a physical barrier regulating nutrient uptake, rather it plays a critical role in homeostasis through its intrinsic innate immune function, pivotal regulation of antigen sensitization, and a bi-directional interplay with the microbiota that evolves with age. In this review we will discuss these functions of the epithelium in the context of food allergy.

Microbiome of the first stool and overweight at age 3 years: A prospective cohort study

BACKGROUND

Several reports have revealed that the first-pass meconium hosts a diverse microbiome, but its clinical significance is not known.

OBJECTIVE

We designed a prospective population-based cohort study to evaluate whether the meconium microbiome predicts subsequent growth in children.

METHODS

The study comprised 212 consecutive newborns with a meconium sample and a follow-up sample at 1 year of age. Trained nurses measured the children for weight and length using standardized techniques. We used next-generation sequencing of bacterial 16S rRNA gene and machine-learning approach for the analysis.

RESULTS

The children with overweight at 3 years of age differed in their meconium microbiome from those with normal weight, having a higher proportion of Bacteroidetes phylum (29% vs 15%, P = .013). Using the machine-learning approach, the gut microbiome at birth predicted subsequent overweight with area under the curve 0.70 (SD 0.04). A lower proportion of Staphylococcus at birth was associated with greater length/height at 1 year (ß = -.68, P = .029) and 2 years of age (β = -.74, P = .030).

CONCLUSIONS

The microbiome of the first-pass meconium predicted subsequent overweight at the age of 3 years. The association between the gut microbiome and overweight appears to start already during pregnancy and at birth.

Microbiome of the first stool after birth and infantile colic

BACKGROUND

Recent studies have shown a diverse microbiome in the first stool after birth. The clinical significance of the microbiome of the first stool is not known. Infantile colic has earlier been associated with the composition of the intestinal microbiome.

METHODS

We set out to test whether the microbiome of the first stool is associated with subsequent infantile colic in a prospective, population-based cohort study of 212 consecutive newborn infants. We used next-generation sequencing of the bacterial 16S rRNA gene.

RESULTS

The newborns who later developed infantile colic (n = 19) had a lower relative abundance of the genus Lactobacillus and the phylum Firmicutes in the first stool than those who remained healthy (n = 139). By using all microbiome data, random forest algorithm classified newborn with subsequent colic and those who remained healthy with area under the curve of 0.66 (SD 0.03) as compared to that of shuffled samples (P value <0.001).

CONCLUSIONS

In this prospective, population-based study, the microbiome of the first-pass meconium was associated with subsequent infantile colic. Our results suggest that the pathogenesis of infantile colic is closely related to the intestinal microbiome at birth.

Microbial Colonization From the Fetus to Early Childhood-A Comprehensive Review

The development of the neonatal gastrointestinal tract microbiota remains a poorly understood process. The interplay between neonatal (gestational age, genetic background), maternal (mode of delivery, nutritional status) and environmental factors (antibiotic exposure, available nutrition) are thought to influence microbial colonization, however, the exact mechanisms are unclear. Derangements in this process likely contribute to various gastrointestinal diseases including necrotizing enterocolitis and inflammatory bowel disease. As such, enhanced understanding of microbiota development may hold the key to significantly reduce the burden of gastrointestinal disease in the pediatric population. The most debatable topics during microbial seeding and possible future treatment approaches will be highlighted in this review.

Perinatal Outcome and Long-Term Infectious Morbidity of Offspring Born to Women with Known Tuberculosis

Objective: To evaluate the perinatal outcome of women with tuberculosis and to assess a possible association between maternal tuberculosis and long-term infectious morbidity of the offspring. Study design: Perinatal outcome and long-term infectious morbidity of offspring of mothers with and without tuberculosis were assessed. The study groups were followed until 18 years of age tracking infectious-related morbidity and infectious-related hospitalizations and then compared. For perinatal outcome, generalized estimation equation models were used. A Kaplan-Meier survival curve was used to compare cumulative incidence of long-term infectious morbidity. A Cox proportional hazards model was conducted to control for confounders. Results: During the study period, 243,682 deliveries were included, of which 46 (0.018%) occurred in women with tuberculosis. Maternal tuberculosis was found to be independently associated with placental abruption, cesarean deliveries, and very low birth weight. However, offspring born to mothers with tuberculosis did not demonstrate higher rates of infectious-related morbidity. Maternal tuberculosis was not noted as an independent risk factor for long-term infectious morbidity of the offspring. Conclusion: In our study, maternal tuberculosis was found to be independently associated with adverse perinatal outcomes. However, higher risk for long-term infectious morbidity of the offspring was not demonstrated. Careful surveillance of these women is required.

Probiotic Supplementation During the Perinatal and Infant Period: Effects on Gut Dysbiosis and Disease

The perinatal period is crucial to the establishment of lifelong gut microbiota. The abundance and composition of microbiota can be altered by several factors such as preterm delivery, formula feeding, infections, antibiotic treatment, and lifestyle during pregnancy. Gut dysbiosis affects the development of innate and adaptive immune responses and resistance to pathogens, promoting atopic diseases, food sensitization, and infections such as necrotizing enterocolitis (NEC). Recent studies have indicated that the gut microbiota imbalance can be restored after a single or multi-strain probiotic supplementation, especially mixtures of Lactobacillus and Bifidobacterium strains. Following the systematic search methodology, the current review addresses the importance of probiotics as a preventive or therapeutic tool for dysbiosis produced during the perinatal and infant period. We also discuss the safety of the use of probiotics in pregnant women, preterm neonates, or infants for the treatment of atopic diseases and infections.

The influence of prenatal and intrapartum antibiotics on intestinal microbiota colonisation in infants: A systematic review

OBJECTIVES

The intestinal microbiota develops in early infancy and is essential for health status early and later in life. In this review we focus on the effect of prenatal and intrapartum maternally administered antibiotics on the infant intestinal microbiota.

METHODS

A systematic literature search was conducted in PubMed and EMBASE. All studies reporting effect on diversity or microbiota profiles were included.

RESULTS

A total of 4.030 records were encountered. A total of 24 articles were included in the final analysis. Infants from mothers exposed to antibiotics during delivery showed a decreased microbial diversity compared to non-exposed infants. The microbiota of infants exposed to antibiotics was characterised by a decreased abundance of Bacteriodetes and Bifidobacteria, with a concurrent increase of Proteobacteria. These effects were most pronounced in term vaginally born infants.

CONCLUSION

Maternal administration of antibiotics seems to have profound effects on the infant gut microbiota colonisation. Interpretation of microbiota aberrations in specific populations, such as preterm and caesarean born infants, is complicated by multiple confounding factors and by lack of high quality studies and high heterogeneity in study design. Further research is needed to investigate the potential short- and long-term clinical consequences of these microbial alterations.

Contributors to Dysbiosis in Very-Low-Birth-Weight Infants

The objective of this commentary was to analyze the causes and outcomes of gut microbiome dysbiosis in preterm infants who are born at very low birth weight (VLBW). The intrauterine development of VLBW infants is interrupted abruptly with preterm birth and followed by extrauterine, health-threatening conditions and sequelae. These infants develop intestinal microbial dysbiosis characterized by low diversity, an overall reduction in beneficial and/or commensal bacteria, and enrichment of opportunistic pathogens of the Gammaproteobacteria class. The origin of VLBW infant dysbiosis is not well understood and is likely the result of a combination of immaturity and medical care. We propose that these factors interact to produce inflammation in the gut, which further perpetuates dysbiosis. Understanding the sources of dysbiosis could result in interventions to reduce gut inflammation, decrease enteric pathology, and improve health outcomes for these vulnerable infants.

Necrotizing Enterocolitis: A Multi-omic Approach and the Role of the Microbiome

Necrotizing enterocolitis (NEC) is a poorly defined disease that primarily affects preterm infants. There has not been much progress in the prevention or treatment of NEC since it became recognized as a common problem in preterm infants. Reasons for this lack of progress include the likelihood that different diseases are being put under the same moniker of "NEC," similar to using "diabetes" for the different diseases it represents. In order to make progress, better delineation of the phenotypes that present as NEC will be necessary to clearly establish their pathophysiology, find specific and sensitive biomarkers, and establish preventative regimens. In this review, we summarize some of the entities that are being called NEC, discuss the pathophysiology of the most classic form of NEC, and provide an overview of how we might proceed in the future to make progress in this field.

Fungi form interkingdom microbial communities in the primordial human gut that develop with gestational age

Fungal and bacterial commensal organisms play a complex role in the health of the human host. Expansion of commensal ecology after birth is a critical period in human immune development. However, the initial fungal colonization of the primordial gut remains undescribed. To investigate primordial fungal ecology, we performed amplicon sequencing and culture-based techniques of first-pass meconium, which forms in the intestine prior to birth, from a prospective observational cohort of term and preterm newborns. Here, we describe fungal ecologies in the primordial gut that develop complexity with advancing gestational age at birth. Our findings suggest homeostasis of fungal commensals may represent an important aspect of human biology present even before birth. Unlike bacterial communities that gradually develop complexity, the domination of the fungal communities of some preterm infants by Saccromycetes, specifically Candida, may suggest a pathologic association with preterm birth.-Willis, K. A., Purvis, J. H., Myers, E. D., Aziz, M. M., Karabayir, I., Gomes, C. K., Peters, B. M., Akbilgic, O., Talati, A. J., Pierre, J. F. Fungi form interkingdom microbial communities in the primordial human gut that develop with gestational age.

Meconium-stained amniotic fluid exposure is associated with a lower incidence of offspring long-term infectious morbidity

OBJECTIVE

Meconium-stained amniotic fluid (MSAF) is a well-established risk factor for immediate adverse neonatal outcomes and was recently suggested to be associated with microbial invasion of the amniotic cavity. We aimed to determine whether MSAF exposure during labor carries a longer lasting impact on pediatric infectious morbidity.

STUDY DESIGN

A population-based cohort analysis was performed including all singleton deliveries occurring between 1991 and 2014 at a single tertiary medical center. Exposure was defined as the presence of MSAF during labor. Hospitalizations of the offspring up to the age of 18 years involving infectious diseases were evaluated. A Kaplan-Meier survival curve was used to compare cumulative morbidity and a Cox regression model to control for confounders.

RESULTS

During the study period, 243 725 deliveries met the inclusion criteria. Of them, 35 897 (14.7%) involved MSAF. Rate of infectious-related hospitalizations of the offspring was significantly lower in children exposed to MSAF as compared with the unexposed group (10.8% vs 11.1%, P < 0.05). Specifically, hospitalizations involving respiratory infections were significantly less common among the MSAF group (5.1% vs 5.6%, P < 0.001). The survival curve demonstrated significantly lower cumulative total infectious morbidity rates in the MSAF-exposed group (log rank P < 0.001). In the Cox model, controlled for maternal age, diabetes, hypertension, mode of delivery, and gestational age, exposed children exhibited lower rates of long-term childhood infectious morbidity (adjusted HR 0.96, 95% CI 0.92-0.99, P < 0.001).

CONCLUSION

Fetal exposure to MSAF during labor and delivery appears to be associated with lower rates of long-term infectious-related hospitalizations in the offspring.

Influence of Early Life, Diet, and the Environment on the Microbiome

Advances in sequencing technology and bioinformatics have greatly enhanced our ability to understand the human microbiome. Over the last decade, a growing body of literature has linked nutrition and the environment to the microbiome and is now thought to be an important contributor to overall health. This paper reviews the literature from the past 10 years to highlight the influence of environmental factors such as diet, early life adversity and stress in shaping and modifying our microbiome towards health and disease. The review shows that many factors such as the mode of delivery, breast milk, stress, diet and medications can greatly influence the development of our gut microbiome and potentially make us more prone to certain diseases. By incorporating environmental factors into models that study the microbiome in the setting of health and disease, may provide a better understanding of disease and potentially new areas of treatment. To highlight this, we will additionally explore the role of the environment and the microbiome in the development of obesity and functional bowel disorders.

The Prenatal Microbiome: A New Player for Human Health

The last few years have featured an increasing interest in the study of the human microbiome and its correlations with health status. Indeed, technological advances have allowed the study of microbial communities to reach a previously unthinkable sensitivity, showing the presence of microbes also in environments usually considered as sterile. In this scenario, microbial communities have been described in the amniotic fluid, the umbilical blood cord, and the placenta, denying a dogma of reproductive medicine that considers the uterus like a sterile womb. This prenatal microbiome may play a role not only in fetal development but also in the predisposition to diseases that may develop later in life, and also in adulthood. Thus, the aim of this review is to report the current knowledge regarding the prenatal microbiome composition, its association with pathological processes, and the future perspectives regarding its manipulation for healthy status promotion and maintenance.