The Gut Microbiome Dynamically Associates with Host Glucose Metabolism throughout Pregnancy: Longitudinal Findings from a Matched Case-Control Study of Gestational Diabetes Mellitus

Microbial Disturbances Caused by Pesticide Exposure and Their Predictive Implications for Gestational Diabetes Mellitus

Previous studies have suggested that pesticide exposure and gut microbiome alterations are associated with gestational diabetes mellitus (GDM) risk. Understanding the complex interactive effect of these factors on GDM is essential. In a cohort of 852 pregnant women, we assessed pesticide levels in serum and analyzed the gut microbiota using 16S rRNA and shotgun metagenomic sequencing. We explored the interactions between pesticides and gut microbiota, assessed their roles in GDM development, and proposed a predictive model based on identified biomarkers. We identified an environmental risk score (ERS), denoting the pesticide mixture level significantly associated with GDM, with the gut microbiota, particularly involving the Dorea branch, playing a crucial mediating role. In addition, we found an interactive effect of pesticide exposure and gut microbiota on GDM risk. Notably, low Prevotella enrichment combined with high ERS arisen from pesticide levels led to a 10.36-fold increased GDM risk. The identified pesticide and gut microbial biomarkers achieved high predictive accuracy for GDM (AUC: 0.833, 95% CI: 0.748-0.918). Collectively, maternal pesticide exposure may induce disrupted microbiome-dependent glycemic alteration, necessitating future assessment of clinical implications. Potential GDM markers can serve as targets for therapeutic intervention caused by pesticides, leading to prevention.

Association of gut microbiota with overweight/obesity combined with gestational diabetes mellitus

Introduction. Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy and negatively affects the health of mothers and infants. The aim of this study was to explore the associations between gut microbiota and the risk of GDM amongst overweight/obese women, and the interaction between gut microbiota dysbiosis and overweight/obesity in pregnant women with GDM.Hypothesis/Gap statement. Previous studies revealed that there may be a link between gut microbiota and GDM and obesity, but these studies have not reported the associations between gut microbiota and the risk of GDM amongst overweight/obese women, whilst the interaction between gut microbiota dysbiosis and overweight/obesity in pregnant women with GDM remains unknown.Aim. Based on a prospective cohort study, we explored the composition of gut microbiota in overweight/obese pregnant women and its association with GDM.Methodology.Participants (n=1820) were enrolled from the Pregnancy Metabolic Disease and Adverse Pregnancy Outcome cohort in Guangzhou, China, between 2019 and 2021. The participants' information and faecal samples were collected, and the relative abundance of faecal microbiota was profiled using 16S rRNA V4 region sequencing. Pregnant women were divided into four groups: non- overweight (NOW)/obese without GDM (OB- NGDM), overweight (OW)/OB- NGDM, NOW/obese with GDM (OB- GDM) and OW/OB- GDM. Linear discriminant analysis effect size (LEfSe) analysis, Spearman's correlation analysis and t- test were performed to estimate the association amongst microbiota, pre- pregnancy BMI and oral glucose tolerance test (OGTT) glucose levels.Results. Blautia, Anaerostipes, Synergistes (P<0.001) and Christensenellaceae_R_7_group (P=0.007) were significantly different between NOW/OB-GDM and OW/OB-GDM groups after adjusting for age. Odoribacter, Anaerostipes, Monoglobus, Romboutsia, Oscillospiraceae__UCG-003, Blautia and Dialisterwere significantly correlated with both OGTT 1 h (P<0.001) and 2 h (P<0.05) blood glucose levels, whilst Lactobacillus(P<0.001) were significantly correlated with OGTT 2 h blood glucose levels. Synergistes(P<0.001) were significantly correlated with OGTT fasting glucose levels, and Megasphaera and Odoribacter(P<0.05) were significantly correlated with pre-pregnancy BMI.Conclusions. GDM and OB/OW women was experiencing microbiota dysbiosis, especially the microbial communities related to glucose metabolism.

Trace Element Exposure during Pregnancy Has a Persistent Influence on Perinatal Gut Microbiota in Mother-Infant Dyads

Trace elements have been recognized as the modifiers of the gut microbiota. However, population-based evidence about their effects on maternal gut microbiota dynamics, as well as the intergenerational impacts on neonatal gut microbiota, has been lacking. We examined the longitudinal microbiota data from mother-infant dyads and demonstrated that maternal trace element exposure played a pivotal role in shaping the composition and similarity of the mother-infant gut microbiota. Specifically, serum levels of cobalt (Co), molybdenum (Mo), and rubidium (Rb) were identified to cause further fluctuation in the shift of the maternal gut microbiota. Antibiotic usage shortly before or on the delivery day, as well as maternal zinc (Zn) exposure, affected the gut microbiota similarity within mother-infant dyads. Rb demonstrated an intergenerational effect on meconium Bifidobacterium abundance by altering its abundance in the maternal gut. Notably, this effect was strengthened in the vaginal delivery group without antibiotic usage, while it was attenuated in the c-section delivery group. Our results suggest that maternal trace element exposure has a persistent influence on perinatal gut microbiota, which offers novel insights into promoting mother and infant health.

Circulating linoleic acid and its interplay with gut microbiota during pregnancy for gestational diabetes mellitus

BACKGROUND

Circulating linoleic acid (LA) levels have been reported to be associated with various metabolic outcomes. However, the role of LA and its interplay with gut microbiota in gestational diabetes mellitus (GDM) remains unclear. This study aimed to investigate the longitudinal association between circulating LA levels during pregnancy and the risk of GDM, and the potential role of gut microbiota.

METHODS

A nested case-control study was conducted within the ongoing Tongji-Huaxi-Shuangliu Birth Cohort in Chengdu, China. Blood and fecal samples were collected during early and middle pregnancy from 807 participants. GDM was diagnosed in middle pregnancy using the International Association of Diabetes and Pregnancy Study Groups criteria. Plasma LA levels were measured using gas chromatography-mass spectrometry, and gut microbiota was analyzed through 16S rRNA gene sequencing and shotgun metagenomic sequencing. A two-sample Mendelian randomization study was conducted using data from the IEU OpenGWAS database and the FinnGen consortium.

RESULTS

Elevated plasma LA levels were associated with a lower risk of GDM in both early (P for trend = 0.002) and middle pregnancy (P for trend = 0.02). Consistently, Mendelian randomization analysis revealed that each unit increase in LA was associated with a 16% reduction in GDM risk (odds ratio: 0.84, 95% confidence interval: 0.72, 0.95). In early pregnancy, higher plasma LA levels were correlated with higher adiponectin levels (P < 0.001) and lower levels of triglycerides (P < 0.001), HbA1c (P = 0.04), and C-peptide (P = 0.04). The LA-accociated microbiota mediated the relationship between LA and C-peptide (P = 0.01). Additionally, the inverse association between LA and GDM was modified by Bilophila (P for interaction = 0.03), with a stronger association observed in participants with lower Bilophila levels in early pregnancy. Metagenomic analyses further showed that the LA-associated pathway (D-galacturonate degradation I) and its key enzyme (EC 4.2.1.7) were associated with metabolic traits.

CONCLUSIONS

Our study provides evidence for an inverse causal association between plasma LA levels during pregnancy and GDM risk, which is both mediated and modified by gut microbiota.

Unraveling the role of the gut microbiome in pregnancy disorders: insights and implications

The gut microbiota is the collective term for the microorganisms that reside in the human gut. In recent years, advances in sequencing technology and bioinformatics gradually revealed the role of gut microbiota in human health. Dramatic changes in the gut microbiota occur during pregnancy due to hormonal and dietary changes, and these changes have been associated with certain gestational diseases such as preeclampsia (PE) and gestational diabetes mellitus (GDM). Modulation of gut microbiota has also been proposed as a potential treatment for these gestational diseases. The present article aims to review current reports on the association between gut microbiota and gestational diseases, explore possible mechanisms, and discuss the potential of probiotics in gestational diseases. Uncovering the link between gut microbiota and gestational diseases could lead to a new therapeutic approach.

Gut-X axis

Recent advances in understanding the modulatory functions of gut and gut microbiota on human diseases facilitated our focused attention on the contribution of the gut to the pathophysiological alterations of many extraintestinal organs, including the liver, heart, brain, lungs, kidneys, bone, skin, reproductive, and endocrine systems. In this review, we applied the "gut-X axis" concept to describe the linkages between the gut and other organs and discussed the latest findings related to the "gut-X axis," including the underlying modulatory mechanisms and potential clinical intervention strategies.

Shenling Guchang prescription ameliorates intestinal barrier inflammation in gestational diabetes rats via TLR4/NF-κB pathway

Gestational diabetes mellitus (GDM) is linked to a greater risk of various maternal and fetal complications, including the possibility of long-term metabolic issues in offspring. Our initial research suggests that the Traditional Chinese Medicine formula, Shenling Guchang prescription (SLGP), may have an impact on the gut microbiota. However, the specific mechanisms through which it affects intestinal barrier inflammation in GDM are still not fully understood. This study explored SLGP's mechanisms in GDM. Firstly, network pharmacology predicted key bioactive constituents targeting toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB), guiding experimental design. Subsequently, the pregnant female rats were induced with GDM through intraperitoneal streptozotocin injection and then divided into control, model, metformin, and SLGP treatment groups. Blood samples were collected for ELISA analysis to measure levels of inflammatory markers, intestinal tissues were examined histologically using hematoxylin-eosin (HE) staining, and western blot analysis was conducted to evaluate TLR4 and NF-κB expression. Relative to control rats, model group animals exhibited significant increases in the levels of inflammatory markers (IL-1β, IL-6, TNF-α, TGF-β, CRP), as well as enhanced TLR4 and p-NF-κB p65 expression, along with intestinal histopathological changes. Treatment with SLGP notably reduced inflammatory markers and protein expression in the colonic tissue of GDM rats, leading to a decrease in histopathological damage. Overall, SLGP was found to modulate the TLR4/NF-κB pathway, resulting in enhancements in insulin resistance and a reduction in inflammatory responses in GDM rats, thereby providing protection for the intestines. This study demonstrates the potential therapeutic effectiveness of SLGP in addressing intestinal inflammation linked to GDM.

Causal Associations Between the Gut Microbiota and Hypertension-Related Traits Through Mendelian Randomization: A Cross-Sectional Cohort Study

Previous studies have suggested a link between the gut microbiome and hypertension-related traits like blood pressure. However, these reports are often limited by weak causal evidence. This study investigates the potential causal association between gut microbiota and hypertension-related traits using Mendelian randomization with summary data from genome-wide association studies. The inverse-variance weighted method revealed that the Clostridium innocuum group (Odds ratio [OR]: 1.0047, 95% confidence interval [CI]: 1.0004-1.0090, p = 0.0336), Eubacterium fissicatena group (OR: 1.0047, 95% CI: 1.0005-1.0088, p = 0.0266), Lachnospiraceae FCS020 group (OR: 1.0063, 95% CI: 1.0004-1.0122, p = 0.0361), and Olsenella (OR: 1.0044, 95% CI: 1.0001-1.0088, p = 0.0430) were associated with an increased risk of hypertension. Conversely, Flavonifractor (OR: 0.9901, 95% CI: 0.9821-0.9982, p = 0.0166), Parabacteroides (OR: 0.9874, 95% CI: 0.9776-0.9972, p = 0.0121), and Senegalimassilia (OR: 0.9907, 95% CI: 0.9842-0.9974, p = 0.0063) were associated with a decreased risk of hypertension. External validation with the Guangdong Gut Microbiome Project confirmed a negative correlation between Parabacteroides and hypertension, potentially through metabolic pathways. These findings provide further evidence supporting the hypothesis that microbes and their metabolites play a role in blood pressure regulation.

Differences in oral microbiota associated with type 2 diabetes mellitus between the Dai and Han populations

BACKGROUND

Type 2 diabetes mellitus (T2DM) development is closely linked to microbiota, influenced by geography, ethnicity, gender, and age. While the relationship between oral microbiota and T2DM has been explored, specific microbiota associated with T2DM in the Dai and Han populations remains unclear. This study aims to compare oral microbiota differences and identify keystone species between these populations, both with and without T2DM.

METHODS

We recruited 28 han participants (6 healthy children, 10 healthy adults, 12 adults with T2DM) and 34 Dai participants (11 healthy children, 10 healthy adults, 13 adults with T2DM). Blood samples were collected for biochemical analysis, and saliva samples underwent DNA extraction and 16S rRNA sequencing.

RESULTS

Age significantly influenced oral microbiota differences between the Dai and Han populations, overshadowing the effects of diabetes. In the Dai population with T2DM, notable increases in Alistipes putredinis, Lactobacillus spp., Faecalibacterium prausnitzii, and Akkermansia muciniphila were observed compared to the Han population. Keystone genera differed, with Fusibacter central to the Dai population's microbial network, while the Han network was more scattered.

CONCLUSION

This is the first comparative analysis of oral microbiota in the Dai and Han populations with T2DM, highlighting age and ethnicity's influence on microbial composition.

Physiological function of gut microbiota and metabolome on successful pregnancy and lactation in the captive Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis)†

Gestation period in captive Yangtze finless porpoise (YFP) is a well-coordinated and dynamic process, involving both systemic and local alterations. The gut microbiota and its connection to fecal metabolites are crucial in supporting fetal development and ensuring maternal health during reproductive stages. This study evaluates changes in the gut microbiota and their correlation with fecal metabolites in captive YFPs during different reproductive stages. The results reveal that microbial community structure changed significantly during reproductive stages, while gut microbial diversity remained stable. The genus unclassified Peptostrptococcaceae, Corynebacterium, and norank KD4-96 were significantly greater in non-pregnancy (NP), Terrisporobacter was significantly greater in lactating (LL), and Clostridium was significantly higher in early-pregnancy (EP) compared to the other groups. The host fecal metabolome exhibited significant alterations during the reproductive stages. Indoxyl sulfate, octadecatrienoic acid, and methionyl-methionine were significantly higher in the NP; galactosylglycerol, chondroitin 6-sulfate, and lumichrome were significantly higher in the EP and mid-pregnancy (MP); and valylleucine and butyryl-l-carnitine were significantly higher in the LL. The altered metabolites were mostly concentrated in pathways associated with arachidonic acid metabolism (significantly altered in NP), leucine, valine, and isoleucine biosynthesis (significantly altered in EP and MP), and glycerophospholipid metabolism (significantly altered in LL compared to others stages). Additionally, we found a strong link between variations in the host metabolism and alterations in the fecal bacteria of captive YFP. In conclusion, this study provides detailed insights into host metabolic and fecal bacterial changes in captive YFP during reproduction stages, providing important knowledge for improving the reproductive management in the captive YFP.

Dynamic changes of gut microbiota between the first and second trimester for women with gestational diabetes mellitus and their correlations with BMI: a nested cohort study in China

INTRODUCTION

Gut microbiota (GM) has been implicated in gestational diabetes mellitus (GDM), yet longitudinal changes across trimesters remain insufficiently explored.

METHODS

This nested cohort study aimed to investigate GM alterations before 24 weeks of gestation and their association with GDM. Ninety-three Chinese participants provided fecal samples during the first and second trimesters. Based on oral glucose tolerance tests, 11 participants were classified as GDM, and 82 as non-diabetic (ND). Using 16S rRNA sequencing, we analyzed both cross-sectional and longitudinal differences in GM structure between those two groups.

RESULTS

In the first trimester, GDM group exhibited lower levels of Bacteroides_H and Acetatifactor compared to ND group (p < 0.05). In the second trimester, GDM individuals showed increased abundance of Fusobacteriota and Firmicutes_D, and genera including Fusobacterium_A and Fournierella, while Anaerotruncus and others decreased (P<0.05). Inflammation-associated genera like Gemmiger_A_73129 and Enterocloster increased, while Megamonas decreased in overweight or obese GDM women, which was not identified in normal-weight women. The ratios of relative abundance of genera Streptococcus, Enterocloster, and Collinsella exceeded 1.5 in the GDM group, particularly in overweight or obese individuals. Inflammatory pathways related to African trypanosomiasis and Staphylococcus aureus infection were predicted to be up-regulated in overweight or obese GDM individuals but not in normal-weight GDM women.

DISCUSSION

This study suggests that GM of women with GDM undergoes significant alterations between the first and second trimesters, potentially linked to inflammation, with more pronounced changes observed in overweight or obese individuals.

Bifidobacterium species serve as key gut microbiome regulators after intervention in gestational diabetes mellitus

Gut microbiome dysbiosis is associated with gestational diabetes mellitus (GDM), and its modulation represents a promising approach for enhancing glycemic control. In this study, we aimed to discover specific alterations in the gut microbiome through lifestyle management. We performed metagenome sequencing on fecal samples and measured short-chain fatty acid (SCFA) in plasma samples from 27 well-controlled GDM pregnancies before and after glycemic control. At the same time, 38 normal glucose tolerance (NGT) samples served as controls. Additionally, we employed two-sample Mendelian Randomization (MR) to validate our findings against Genome-Wide Association Study (GWAS) database. Our dynamic analysis revealed Bifidobacterium genus increased in GDM patients after intervention. The MR analysis confirmed that the family of Bifidobacteriaceae (OR 0.929, 95% CI, 0.886-0.975; P = 0.003) was the only negatively associated family with GDM. Further analysis indicated the increased abundance of Bifidobacterium species were negatively correlated with glycemic traits (Spearman rho mean - 0.32 ± 0.34) but positively correlated with plasma SCFA levels (Spearman rho mean 0.24 ± 0.19). Functional analysis revealed that the quorum-sensing pathway had the strongest effect on the ability of Bifidobacterium to promote glucose homeostasis (Spearman rho = -0.34), suggesting its role in regulating intestinal microbiota. Finally, the multivariable MR analysis demonstrated that two pathways, COLANSYN PWY and PWY 7323, responsible for cell surface compound synthesis in gram-negative bacteria, mediated 14.83% (P = 0.017) and 16.64% (P = 0.049) of the protective effects of Bifidobacteriaceae against GDM, respectively. In summary, Bifidobacterium is an effective gut microbiota regulator for GDM-related glucose homeostasis.

Clinical significance of the genetically variable landscape of the gut microbiome in patients with gestational diabetes mellitus patients

Background

The composition of the gut microbiome has been recorted to be strongly associated with gestational diabetes mellitus (GDM), but mutational characterization of the microbiome in patients with GDM has been overlooked. Here, we revealed the genetic variation landscape of the gut microbiome and assessed its clinical significance in a cohort of patients with GDM.

Methods

We employed a macrogenomic dataset made up of a discovery cohort of 54 cases and a validation cohort of 220 cases to screen for high-abundance microbial flora and identified single nucleotide variants (SNVs) and insertions/deletions (indels). Subsequently, we analyzed the mutation spectra of genomes of the intestinal flora by using the previously identified SNVs and identified mutation signatures. Additionally, we utilized the Random Forest algorithm to identify key differential SNVs and elucidated their biological functions and associations with the clinicopathological parameters of GDM.

Results

We screened 15 key microbial flora and found that the GDM group had more SNVs and indels in the intestinal flora than the control group, with a significant increase in C > T and T > C base mutations and were more susceptible to sequence mutations. Compared to the control group, the GDM group underwent a more significant evolution, as evidenced by the presence of a unique mutational spectrum and mutational characteristics. Random Forest algorithm analysis showed that the combined characterization of five gut microbial species and 21 SNV-related markers was effective in distinguishing between GDM and control subjects in both discovery (area under the curve (AUC) = 0.86) and validation (AUC = 0.73) sets. These markers also revealed that GDM is strongly associated with sphingolipids, galactose, and proteins containing the DUF structural domain.

Conclusions

The GDM intestinal flora has unique mutational features that correlate significantly with clinicopathological involvement and may be involved in the development of the disease.

Suppression of certain intestinal microbiota metabolites may lead to gestational diabetes in mice fed a high-fat diet

Background

We aim to establish a gestational diabetes mellitus (GDM) mouse model with mice fed with a high-fat diet (HFD) in comparison with pregnant mice with normal blood glucose levels to investigate the role of intestinal microbiota in the development of HFD-induced GDM.

Methods

We divided healthy 6-week-old female C57BL mice into an HFD-induced GDM group and a normal diet group. Their bacterial flora and metabolites in intestinal fecal exosomes were co-analyzed using 16 s multi-region sequencing and compared.

Findings

Alpha (α) diversity was lower within the model group compared to the control group. Beta (β) diversity was significantly different between the two groups. The relative abundances of Lactobacillus, Actinomyces, Rothia, and Bacteroidetes were significantly different between the two groups. Fermentation and nitrate consumption were significantly higher in the GDM group. Multiple bacteria were associated with glycerophosphocholine, S-methyl-5'-thioadenosine, quinolinate, galactinol, deoxyadenosine, DL-arginine, and 2-oxoadenic acid.

Interpretation

Imbalances in the production of Lactobacillus, Bacteroidetes, Actinomyces, and Rothia and their related metabolites may lead to metabolic disturbances in GDM. These indicators may be used to assess changes affecting the intestinal microbiota during pregnancy and thus help modulate diet and alter blood glucose.

Distinct Plasma Metabolomic and Gut Microbiome Profiles after Gestational Diabetes Mellitus Diet Treatment: Implications for Personalized Dietary Interventions

Gestational diabetes mellitus (GDM) triggers alterations in the maternal microbiome. Alongside metabolic shifts, microbial products may impact clinical factors and influence pregnancy outcomes. We investigated maternal microbiome-metabolomic changes, including over 600 metabolites from a subset of the "Choosing Healthy Options in Carbohydrate Energy" (CHOICE) study. Women diagnosed with GDM were randomized to a diet higher in complex carbohydrates (CHOICE, n = 18, 60% complex carbohydrate/25% fat/15% protein) or a conventional GDM diet (CONV, n = 16, 40% carbohydrate/45% fat/15% protein). All meals were provided. Diets were eucaloric, and fiber content was similar. CHOICE was associated with increases in trimethylamine N-oxide, indoxyl sulfate, and several triglycerides, while CONV was associated with hippuric acid, betaine, and indole propionic acid, suggestive of a healthier metabolome. Conversely, the microbiome of CHOICE participants was enriched with carbohydrate metabolizing genes and beneficial taxa such as Bifidobacterium adolescentis, while CONV was associated with inflammatory pathways including antimicrobial resistance and lipopolysaccharide biosynthesis. We also identified latent metabolic groups not associated with diet: a metabolome associated with less of a decrease in fasting glucose, and another associated with relatively higher fasting triglycerides. Our results suggest that GDM diets produce specific microbial and metabolic responses during pregnancy, while host factors also play a role in triglycerides and glucose metabolism.

Relationship between gut microbiota and the pathogenesis of gestational diabetes mellitus: a systematic review

Introduction

Gestational diabetes mellitus (GDM) is a form of gestational diabetes mellitus characterized by insulin resistance and abnormal function of pancreatic beta cells. In recent years, genomic association studies have revealed risk and susceptibility genes associated with genetic susceptibility to GDM. However, genetic predisposition cannot explain the rising global incidence of GDM, which may be related to the increased influence of environmental factors, especially the gut microbiome. Studies have shown that gut microbiota is closely related to the occurrence and development of GDM. This paper reviews the relationship between gut microbiota and the pathological mechanism of GDM, in order to better understand the role of gut microbiota in GDM, and to provide a theoretical basis for clinical application of gut microbiota in the treatment of related diseases.

Methods

The current research results on the interaction between GDM and gut microbiota were collected and analyzed through literature review. Keywords such as "GDM", "gut microbiota" and "insulin resistance" were used for literature search, and the methodology, findings and potential impact on the pathophysiology of GDM were systematically evaluated.

Results

It was found that the composition and diversity of gut microbiota were significantly associated with the occurrence and development of GDM. Specifically, the abundance of certain gut bacteria is associated with an increased risk of GDM, while other changes in the microbiome may be associated with improved insulin sensitivity. In addition, alterations in the gut microbiota may affect blood glucose control through a variety of mechanisms, including the production of short-chain fatty acids, activation of inflammatory pathways, and metabolism of the B vitamin group.

Discussion

The results of this paper highlight the importance of gut microbiota in the pathogenesis of GDM. The regulation of the gut microbiota may provide new directions for the treatment of GDM, including improving insulin sensitivity and blood sugar control through the use of probiotics and prebiotics. However, more research is needed to confirm the generality and exact mechanisms of these findings and to explore potential clinical applications of the gut microbiota in the management of gestational diabetes. In addition, future studies should consider the interaction between environmental and genetic factors and how together they affect the risk of GDM.

Spatiotemporal patterns of the pregnancy microbiome and links to reproductive disorders

The microbiome of females undergoes extensive remodeling during pregnancy, which is likely to have an impact on the health of both mothers and offspring. Nevertheless, large-scale integrated investigations characterizing microbiome dynamics across key body habitats are lacking. Here, we performed an extensive meta-analysis that compiles and analyzes microbiome profiles from  >10,000 samples across the gut, vagina, and oral cavity of pregnant women from diverse geographical regions. We have unveiled unexpected variations in the taxonomic, functional, and ecological characteristics of microbial communities throughout the course of pregnancy. The gut microbiota showed distinct trajectories between Western and non-Western populations. The vagina microbiota exhibited fluctuating transitions at the genus level across gestation, while the oral microbiota remained relatively stable. We also identified distinctive microbial signatures associated with prevalent pregnancy-related disorders, including opposite variations in the oral and gut microbiota of patients with gestational diabetes and disrupted microbial networks in preterm birth. This study establishes a comprehensive atlas of the pregnancy microbiome by integrating multidimensional datasets and offers foundational insights into the intricate interplay between microbes and host factors that underlie reproductive health.

Interactions between host and gut microbiota in gestational diabetes mellitus and their impacts on offspring

Gestational diabetes mellitus (GDM) is characterized by insulin resistance and low-grade inflammation, and most studies have demonstrated gut dysbiosis in GDM pregnancies. Overall, they were manifested as a reduction in microbiome diversity and richness, depleted short chain fatty acid (SCFA)-producing genera and a dominant of Gram-negative pathogens releasing lipopolysaccharide (LPS). The SCFAs functioned as energy substance or signaling molecules to interact with host locally and beyond the gut. LPS contributed to pathophysiology of diseases through activating Toll-like receptor 4 (TLR4) and involved in inflammatory responses. The gut microbiome dysbiosis was not only closely related with GDM, it was also vital to fetal health through vertical transmission. In this review, we summarized gut microbiota signature in GDM pregnancies of each trimester, and presented a brief introduction of microbiome derived SCFAs. We then discussed mechanisms of microbiome-host interactions in the physiopathology of GDM and associated metabolic disorders. Finally, we compared offspring microbiota composition from GDM with that from normal pregnancies, and described the possible mechanism.

Microbiome in Female Reproductive Health: Implications for Fertility and Assisted Reproductive Technologies

The microbiome plays a critical role in the process of conception and the outcomes of pregnancy. Disruptions in microbiome homeostasis in women of reproductive age can lead to various pregnancy complications, which significantly impact maternal and fetal health. Recent studies have associated the microbiome in the female reproductive tract (FRT) with assisted reproductive technology (ART) outcomes, and restoring microbiome balance has been shown to improve fertility in infertile couples. This review provides an overview of the role of the microbiome in female reproductive health, including its implications for pregnancy outcomes and ARTs. Additionally, recent advances in the use of microbial biomarkers as indicators of pregnancy disorders are summarized. A comprehensive understanding of the characteristics of the microbiome before and during pregnancy and its impact on reproductive health will greatly promote maternal and fetal health. Such knowledge can also contribute to the development of ARTs and microbiome-based interventions.

Advances in fecal microbiota transplantation for the treatment of diabetes mellitus

Diabetes mellitus (DM) refers to a group of chronic diseases with global prevalence, characterized by persistent hyperglycemia resulting from various etiologies. DM can harm various organ systems and lead to acute or chronic complications, which severely endanger human well-being. Traditional treatment mainly involves controlling blood sugar levels through replacement therapy with drugs and insulin; however, some patients still find a satisfactory curative effect difficult to achieve. Extensive research has demonstrated a close correlation between enteric dysbacteriosis and the pathogenesis of various types of DM, paving the way for novel therapeutic approaches targeting the gut microbiota to manage DM. Fecal microbiota transplantation (FMT), a method for re-establishing the intestinal microbiome balance, offers new possibilities for treating diabetes. This article provides a comprehensive review of the correlation between DM and the gut microbiota, as well as the current advancements in FMT treatment for DM, using FMT as an illustrative example. This study aims to offer novel perspectives and establish a theoretical foundation for the clinical diagnosis and management of DM.

Intestinal flora and pregnancy complications: Current insights and future prospects

Numerous studies have demonstrated the pivotal roles of intestinal microbiota in many physiopathological processes through complex interactions with the host. As a unique period in a woman's lifespan, pregnancy is characterized by changes in hormones, immunity, and metabolism. The gut microbiota also changes during this period and plays a crucial role in maintaining a healthy pregnancy. Consequently, anomalies in the composition and function of the gut microbiota, namely, gut microbiota dysbiosis, can predispose individuals to various pregnancy complications, posing substantial risks to both maternal and neonatal health. However, there are still many controversies in this field, such as "sterile womb" versus "in utero colonization." Therefore, a thorough understanding of the roles and mechanisms of gut microbiota in pregnancy and its complications is essential to safeguard the health of both mother and child. This review provides a comprehensive overview of the changes in gut microbiota during pregnancy, its abnormalities in common pregnancy complications, and potential etiological implications. It also explores the potential of gut microbiota in diagnosing and treating pregnancy complications and examines the possibility of gut-derived bacteria residing in the uterus/placenta. Our aim is to expand knowledge in maternal and infant health from the gut microbiota perspective, aiding in developing new preventive and therapeutic strategies for pregnancy complications based on intestinal microecology.

Maternal gut microbiota in the health of mothers and offspring: from the perspective of immunology

Due to the physiological alteration during pregnancy, maternal gut microbiota changes following the metabolic processes. Recent studies have revealed that maternal gut microbiota is closely associated with the immune microenvironment in utero during pregnancy and plays a vital role in specific pregnancy complications, including preeclampsia, gestational diabetes, preterm birth and recurrent miscarriages. Some other evidence has also shown that aberrant maternal gut microbiota increases the risk of various diseases in the offspring, such as allergic and neurodevelopmental disorders, through the immune alignment between mother and fetus and the possible intrauterine microbiota. Probiotics and the high-fiber diet are effective inventions to prevent mothers and fetuses from diseases. In this review, we summarize the role of maternal gut microbiota in the development of pregnancy complications and the health condition of future generations from the perspective of immunology, which may provide new therapeutic strategies for the health management of mothers and offspring.

Dynamics of the Gut Microbiota and Faecal and Serum Metabolomes during Pregnancy-A Longitudinal Study

Normal pregnancy involves numerous physiological changes, including changes in hormone levels, immune responses, and metabolism. Although several studies have shown that the gut microbiota may have an important role in the progression of pregnancy, these findings have been inconsistent, and the relationship between the gut microbiota and metabolites that change dynamically during and after pregnancy remains to be clarified. In this longitudinal study, we comprehensively profiled the temporal dynamics of the gut microbiota, Bifidobacterium communities, and serum and faecal metabolomes of 31 women during their pregnancies and postpartum periods. The microbial composition changed as gestation progressed, with the pregnancy and postpartum periods exhibiting distinct bacterial community characteristics, including significant alterations in the genera of the Lachnospiraceae or Ruminococcaceae families, especially the Lachnospiraceae FCS020 group and Ruminococcaceae UCG-003. Metabolic dynamics, characterised by changes in nutrients important for fetal growth (e.g., docosatrienoic acid), anti-inflammatory metabolites (e.g., trans-3-indoleacrylic acid), and steroid hormones (e.g., progesterone), were observed in both serum and faecal samples during pregnancy. Moreover, a complex correlation was identified between the pregnancy-related microbiota and metabolites, with Ruminococcus1 and Ruminococcaceae UCG-013 making important contributions to changes in faecal and serum metabolites, respectively. Overall, a highly coordinated microbiota-metabolite regulatory network may underlie the pregnancy process. These findings provide a foundation for enhancing our understanding of the molecular processes occurring during the progression of pregnancy, thereby contributing to nutrition and health management during this period.

Interaction and Metabolic Pathways: Elucidating the Role of Gut Microbiota in Gestational Diabetes Mellitus Pathogenesis

Gestational diabetes mellitus (GDM) is a complex metabolic condition during pregnancy with an intricate link to gut microbiota alterations. Throughout gestation, notable shifts in the gut microbial component occur. GDM is marked by significant dysbiosis, with a decline in beneficial taxa like Bifidobacterium and Lactobacillus and a surge in opportunistic taxa such as Enterococcus. These changes, detectable in the first trimester, hint as the potential early markers for GDM risk. Alongside these taxa shifts, microbial metabolic outputs, especially short-chain fatty acids and bile acids, are perturbed in GDM. These metabolites play pivotal roles in host glucose regulation, insulin responsiveness, and inflammation modulation, which are the key pathways disrupted in GDM. Moreover, maternal GDM status influences neonatal gut microbiota, indicating potential intergenerational health implications. With the advance of multi-omics approaches, a deeper understanding of the nuanced microbiota-host interactions via metabolites in GDM is emerging. The reviewed knowledge offers avenues for targeted microbiota-based interventions, holding promise for innovative strategies in GDM diagnosis, management, and prevention.

Methodological Considerations in Longitudinal Analyses of Microbiome Data: A Comprehensive Review

Biological processes underlying health and disease are inherently dynamic and are best understood when characterized in a time-informed manner. In this comprehensive review, we discuss challenges inherent in time-series microbiome data analyses and compare available approaches and methods to overcome them. Appropriate handling of longitudinal microbiome data can shed light on important roles, functions, patterns, and potential interactions between large numbers of microbial taxa or genes in the context of health, disease, or interventions. We present a comprehensive review and comparison of existing microbiome time-series analysis methods, for both preprocessing and downstream analyses, including differential analysis, clustering, network inference, and trait classification. We posit that the careful selection and appropriate utilization of computational tools for longitudinal microbiome analyses can help advance our understanding of the dynamic host-microbiome relationships that underlie health-maintaining homeostases, progressions to disease-promoting dysbioses, as well as phases of physiologic development like those encountered in childhood.

Maternal and infant microbiome: next-generation indicators and targets for intergenerational health and nutrition care

Microbes are commonly sensitive to shifts in the physiological and pathological state of their hosts, including mothers and babies. From this perspective, the microbiome may be a good indicator for diseases during pregnancy and has the potential to be used for perinatal health monitoring. This is embodied in the application of microbiome from multi body sites for auxiliary diagnosis, early prediction, prolonged monitoring, and retrospective diagnosis of pregnancy and infant complications, as well as nutrition management and health products developments of mothers and babies. Here we summarized the progress in these areas and explained that the microbiome of different body sites is sensitive to different diseases and their microbial biomarkers may overlap between each other, thus we need to make a diagnosis prudently for those diseases. Based on the microbiome variances and additional anthropometric and physical data, individualized responses of mothers and neonates to meals and probiotics/prebiotics were predictable, which is of importance for precise nutrition and probiotics/prebiotics managements and developments. Although a great deal of encouraging performance was manifested in previous studies, the efficacy could be further improved by combining multi-aspect data such as multi-omics and time series analysis in the future. This review reconceptualizes maternal and infant health from a microbiome perspective, and the knowledge in it may inspire the development of new options for the prevention and treatment of adverse pregnancy outcomes and bring a leap forward in perinatal health care.

Preventing Gestational Diabetes with a Healthy Gut Diet: Protocol for a Pilot, Feasibility Randomized Controlled Trial

Around 14% of pregnancies globally are affected by gestational diabetes mellitus (GDM), making it one of the most common disorders experienced by women in pregnancy. While dietary, physical activity and supplement interventions have been implemented to prevent GDM, with varying levels of success, altering the gut microbiota through diet is a promising strategy for prevention. Several studies have demonstrated that women with GDM likely have a different gut microbiota to pregnant women without GDM, demonstrating that the gut microbiota may play a part in glycemic control and the development of GDM. To date, there have been no randomized controlled trials using diet to alter the gut microbiota in pregnancy with the aim of preventing GDM. Here, we present the study protocol for a single-blind randomized controlled trial which aims to determine the effectiveness of the Healthy Gut Diet on reducing the diagnosis of GDM in pregnant women with one or more risk factors. Consenting women will be randomized into either the Healthy Gut Diet intervention group or the usual care (control) group after 11 weeks gestation. The women in the intervention group will receive three telehealth counseling appointments with an Accredited Practicing Dietitian with the aim of educating and empowering these women to build a healthy gut microbiota through their diet. The intervention was co-designed with women who have lived experience of GDM and incorporates published behavior change techniques. The control group will receive the usual care and will also be shown a brief (3 min) video on general healthy eating in pregnancy. The primary outcome is the diagnosis of GDM at any stage of the pregnancy. Secondary outcomes include changes to gut microbiota composition and diversity; gestational weight gain; maternal and infant outcomes; management of GDM (where relevant); dietary quality and intake; physical activity; and depression scoring. We aim to recruit 120 women over 16 months. Recruitment commenced in January 2023. The trial has been registered with the Australian New Zealand Clinical Trials Registry (ACTRN12622001285741).

Composition of the intestinal microbiota and its variations between the second and third trimesters in women with gestational diabetes mellitus and without gestational diabetes mellitus

Objective

This study was designed to explore the composition of the intestinal microbiota and its longitudinal variation between the second trimester (T2) and the third trimester (T3) in women with gestational diabetes mellitus (GDM) and pregnant women with normal glucose tolerance.

Methods

This observational study was conducted at Peking Union Medical College Hospital (PUMCH). Women with GDM and pregnant women with normal glucose tolerance were enrolled in the study, and fecal samples were collected during T2 (weeks 24~28) and T3 (weeks 34~38). Fecal samples were analyzed from 49 women with GDM and 42 pregnant women with normal glucose tolerance. The 16S rRNA gene amplicon libraries were sequenced to analyze the microbiota and QIIME2 was used to analyze microbiome bioinformatics.

Results

The four dominant phyla that Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria which accomplish about 99% of the total relative abundance did not significantly change between the T2 and T3 in the GDM and healthy groups. At the genus level, the relative abundance of Scardovia (0 vs. 0.25%, P = 0.041) and Propionibacterium (0 vs. 0.29%, P = 0.041) increased significantly in the control group, but not in the GDM group. At the phylum level, the relative abundance of Firmicutes and Actinobacteria was significantly different between women with GDM and pregnant women with normal glucose tolerance in both T2 and T3. In T2 and T3, the relative abundances of unidentified_Lachnospiraceae, Blautia, and Parabacteroides were significantly higher in the GDM group than in the control group (P<0.05). The relative abundance of Bifidobacterium in the GDM group was lower than in the control group in both T2 and T3.

Conclusions

The intestinal microbiota composition was stable from T2 to T3 in the GDM and control groups; however, the intestinal microbiota composition was different between the two groups.