Maternal gestational diabetes mellitus associates with altered gut microbiome composition and head circumference abnormalities in male offspring.

The impact of gestational diabetes mellitus (GDM) on maternal or infant microbiome trajectory remains poorly understood. Utilizing large-scale longitudinal fecal samples from 264 mother-baby dyads, we present the gut microbiome trajectory of the mothers throughout pregnancy and infants during the first year of life. GDM mothers had a distinct microbiome diversity and composition during the gestation period. GDM leaves fingerprints on the infant's gut microbiome, which are confounded by delivery mode. Further, Clostridium species positively correlate with a larger head circumference at month 12 in male offspring but not females. The gut microbiome of GDM mothers with male fetuses displays depleted gut-brain modules, including acetate synthesis I and degradation and glutamate synthesis II. The gut microbiome of female infants of GDM mothers has higher histamine degradation and dopamine degradation. Together, our integrative analysis indicates that GDM affects maternal and infant gut composition, which is associated with sexually dimorphic infant head growth.

Mommy's microbes: Gestational diabetes mellitus shapes the maternal and infant gut microbiome.

Gestational diabetes mellitus (GDM) is associated with increased risk of metabolic and neurodevelopmental disorders in offspring. In this issue of Cell Host & Microbe, Wang et al. provide evidence that changes in the gut microbiome of mothers with GDM may lead to dysbiosis in their infants and altered development in a sex-dependent manner.

A comparison of the breast milk microbiota from women diagnosed with gestational diabetes mellitus and women without gestational diabetes mellitus.

BACKGROUND: Human breast milk (HBM) is a contributing factor in modulating the infant's gut microbiota, as it contains bacteria that are directly transferred to the infant during breastfeeding. It has been shown that children of women diagnosed with gestational diabetes mellitus (GDM) have a different gut microbiota compared to children of women without GDM. Our hypothesis is therefore that women with GDM have a different HBM microbiota, which may influence the metabolic function and capacity of the child later in life. The aim of this study was to investigate whether women with GDM have a different breast milk microbiota 1-3 weeks postpartum compared to women without GDM. METHODS: In this case-control study, a total of 45 women were included: 18 women with GDM and 27 women without GDM. A milk sample was collected from each participant 1 to 3 weeks postpartum and the bacterial composition was examined by 16 S rRNA gene sequencing targeting the V4 region. RESULTS: High relative abundances of Streptococcus and Staphylococcus were present in samples from both women with and without GDM. No difference could be seen in either alpha diversity, beta diversity, or specific taxa between groups. CONCLUSION: Our results did not support the existence of a GDM-associated breast milk microbiota at 1-3 weeks postpartum. Further research is needed to fully understand the development of the gut microbiota of infants born to mothers with GDM.

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.

Detection of Hanseniaspora opuntiae in anovaginal samples of pregnant women in Rio de Janeiro, Brazil-a case report.

In this study, we report the first isolation of Hanseniaspora opuntiae obtained from four pregnant women in Brazil. Clinical isolates were obtained from four samples taken between 35 and 37 gestational weeks, as part of the routine antenatal care for maternal colonization screening for Streptococcus agalactiae group B. The patients were immunocompetent, with two of them diagnosed with gestational diabetes mellitus. Species identification was performed by MALDI-TOF MS and rDNA sequencing. While Hanseniaspora species have not traditionally been considered a typical opportunist pathogen, our findings emphasize the importance of investigating and screening for Hanseniaspora in pregnant populations, highlighting H. opuntiae as a potential agent of human infections.

Network impact of a single-time-point microbial sample.

The human microbiome plays a crucial role in determining our well-being and can significantly influence human health. The individualized nature of the microbiome may reveal host-specific information about the health state of the subject. In particular, the microbiome is an ecosystem shaped by a tangled network of species-species and host-species interactions. Thus, analysis of the ecological balance of microbial communities can provide insights into these underlying interrelations. However, traditional methods for network analysis require many samples, while in practice only a single-time-point microbial sample is available in clinical screening. Recently, a method for the analysis of a single-time-point sample, which evaluates its 'network impact' with respect to a reference cohort, has been applied to analyze microbial samples from women with Gestational Diabetes Mellitus. Here, we introduce different variations of the network impact approach and systematically study their performance using simulated 'samples' fabricated via the Generalized Lotka-Volttera model of ecological dynamics. We show that the network impact of a single sample captures the effect of the interactions between the species, and thus can be applied to anomaly detection of shuffled samples, which are 'normal' in terms of species abundance but 'abnormal' in terms of species-species interrelations. In addition, we demonstrate the use of the network impact in binary and multiclass classifications, where the reference cohorts have similar abundance profiles but different species-species interactions. Individualized analysis of the human microbiome has the potential to improve diagnosis and personalized treatments.

The impact of gestational diabetes on functional capacity of the infant gut microbiome is modest and transient.

Gestational diabetes mellitus (GDM) is a metabolic complication that manifests as hyperglycemia during the later stages of pregnancy. In high resource settings, careful management of GDM limits risk to the pregnancy, and hyperglycemia typically resolves after birth. At the same time, previous studies have revealed that the gut microbiome of infants born to mothers who experienced GDM exhibit reduced diversity and reduction in the abundance of several key taxa, including Lactobacillus. What is not known is what the functional consequences of these changes might be. In this case control study, we applied 16S rRNA sequence surveys and metatranscriptomics to profile the gut microbiome of 30 twelve-month-old infants - 16 from mothers with GDM, 14 from mothers without - to examine the impact of GDM during pregnancy. Relative to the mode of delivery and sex of the infant, maternal GDM status had a limited impact on the structure and function of the developing microbiome. While GDM samples were associated with a decrease in alpha diversity, we observed no effect on beta diversity and no differentially abundant taxa. Further, while the mode of delivery and sex of infant affected the expression of multiple bacterial pathways, much of the impact of GDM status on the function of the infant microbiome appears to be lost by twelve months of age. These data may indicate that, while mode of delivery appears to impact function and diversity for longer than anticipated, GDM may not have persistent effects on the function nor composition of the infant gut microbiome.

Association of gastrointestinal microbiome and obesity with gestational diabetes mellitus-an updated globally based review of the high-quality literatures.

OBJECTIVES: The purpose of this review is to investigate the relationship between gastrointestinal microbiome, obesity, and gestational diabetes mellitus (GDM) in an objective manner. METHODS: We conducted a thorough and comprehensive search of the English language literatures published in PubMed, Web of Science, and the Cochrane Library from the establishment of the library until 12 December 2023. Our search strategy included both keywords and free words searches, and we strictly applied inclusion and exclusion criteria. Meta-analyses and systematic reviews were prepared. RESULTS: Six high-quality literature sources were identified for meta-analysis. However, after detailed study and analysis, a certain degree of heterogeneity was found, and the credibility of the combined analysis results was limited. Therefore, descriptive analyses were conducted. The dysbiosis of intestinal microbiome, specifically the ratio of Firmicutes/Bacteroides, is a significant factor in the development of metabolic diseases such as obesity and gestational diabetes. Patients with intestinal dysbiosis and obesity are at a higher risk of developing GDM. CONCLUSIONS: During pregnancy, gastrointestinal microbiome disorders and obesity may contribute to the development of GDM, with all three factors influencing each other. This finding could aid in the diagnosis and management of patients with GDM through further research on their gastrointestinal microbiome.

Gut dysbiosis contributes to SCFAs reduction-associated adipose tissue macrophage polarization in gestational diabetes mellitus.

AIMS: The prevalence of gestational diabetes mellitus (GDM) has spurred investigations into various interconnected factors, among which gut dysbiosis is notably prominent. Although gut dysbiosis is strongly associated with GDM, the specific role of the gut microbiome in the pathogenesis of GDM remains unknown. This study aims to explore the pathogenesis of GDM from gut microbiota. MATERIALS AND METHODS: In our study, we constructed two GDM mice models: one induced by a high-fat diet (HFD) and the other through fecal microbiota transplantation (FMT) from GDM patients. In vitro, we used a co-culture system of RAW264.7 and 3T3-L1 adipocytes. KEY FINDINGS: We induced a GDM-like state in pregnant mice by FMT from GDM patients, which was consistent with the HFD model. A potential mechanism identified involves the diminished abundance of SCFA-producing microbiota, which reduces SCFAs, particularly propionic acid and butyric acid. In vitro, butyric and propionic acids were observed to alleviate LPS-induced TLR4-NF-κB activation, thereby reducing inflammation levels and inhibiting adipose insulin resistance via the PI3K/AKT signaling pathway. This reduction appears to trigger the polarization of adipose tissue macrophages toward M1 and promote insulin resistance in adipose tissue. SIGNIFICANCE: Our study fills this knowledge gap by finding that alterations in gut microbiota have an independent impact on hyperglycemia and insulin resistance in the GDM state. In vivo and in vitro, gut dysbiosis is linked to adipose tissue inflammation and insulin resistance via the bacterial product SCFAs in the GDM state, providing new insights into the pathogenesis of GDM.

Veillonella and Bacteroides are associated with gestational diabetes mellitus exposure and gut microbiota immaturity.

BACKGROUND: Dysbiosis during childhood impacts the configuration and maturation of the microbiota. The immaturity of the infant microbiota is linked with the development of inflammatory, allergic, and dysmetabolic diseases. AIMS: To identify taxonomic changes associated with age and GDM and classify the maturity of the intestinal microbiota of children of mothers with GDM and children without GDM (n-GDM). METHODS: Next-generation sequencing was used to analyze the V3-V4 region of 16S rRNA gene. QIIME2 and Picrust2 were used to determine the difference in the relative abundance of bacterial genera between the study groups and to predict the functional profile of the intestinal microbiota. RESULTS: According to age, the older GDM groups showed a lower alpha diversity and different abundance of Enterobacteriaceae, Veillonella, Clostridiales, and Bacteroides. Regarding the functional profile, PWY-7377 and K05895 associated with Vitamin B12 metabolism were reduced in GDM groups. Compared to n-GDM group, GDM offspring had microbiota immaturity as age-discriminatory taxa in random forest failed to classify GDM offspring according to developmental age (OOB error 81%). Conclusion. Offspring from mothers with GDM have a distinctive taxonomic profile related to taxa associated with gut microbiota immaturity.

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.

Cross-Sectional and Prospective Association of Serum 25-Hydroxyvitamin D with Gut Mycobiota during Pregnancy among Women with Gestational Diabetes.

SCOPE: Little is known about the effect of blood vitamin D status on the gut mycobiota (i.e., fungi), a crucial component of the gut microbial ecosystem. The study aims to explore the association between 25-hydroxyvitamin D [25(OH)D] and gut mycobiota and to investigate the link between the identified mycobial features and blood glycemic traits. METHODS AND RESULTS: The study examines the association between serum 25(OH)D levels and the gut mycobiota in the Westlake Precision Birth Cohort, which includes pregnant women with gestational diabetes mellitus (GDM). The study develops a genetic risk score (GRS) for 25(OH)D to validate the observational results. In both the prospective and cross-sectional analyses, the vitamin D is associated with gut mycobiota diversity. Specifically, the abundance of Saccharomyces is significantly lower in the vitamin D-sufficient group than in the vitamin D-deficient group. The GRS of 25(OH)D is inversely associated with the abundance of Saccharomyces. Moreover, the Saccharomyces is positively associated with blood glucose levels. CONCLUSION: Blood vitamin D status is associated with the diversity and composition of gut mycobiota in women with GDM, which may provide new insights into the mechanistic understanding of the relationship between vitamin D levels and metabolic health.

Imbalance of gut microbiota in gestational diabetes.

AIM: To investigate the differences in gut microbiota composition among nonpregnant women of reproductive age, healthy pregnant women, and gestational diabetes (GD) patients. METHODS: A total of 45 outpatients were enrolled and divided into three groups: nonpregnant women of reproductive age (control group, n = 23), healthy pregnant women (normal group, n = 10), and GD patients (GD group, n = 12). Faecal samples were collected and sequenced using 16S rRNA gene sequencing to analyse the microbial composition. RESULTS: (1) Pregnant patients exhibited an increase in the abundance of Streptococcus (Pnormal = 0.01286, PGD = 0.002965) and Blautia (Pnormal = 0.0003924, PGD = 0.000246) but a decrease in the abundance of Roseburia (Pnormal = 0.0361, PGD = 0.007075), Phascolarctobacterium (Pnormal = 0.0003906, PGD = 0.02499) and Lachnoclostridium (Pnormal = 0.0003906, PGD = 0.03866). (2) Compared with healthy pregnant women, GD patients had an excessive increase in Streptococcus abundance and decrease in Roseburia abundance. The increase in Blautia abundance and the decrease in Phascolarctobacterium and Lachnoclostridium abundance in GD patients were less than those in healthy pregnant women. (3) The abundance of Faecalibacterium prausnitzii decreased significantly in GD patients (PGD = 0.02985) but not in healthy pregnant patients (Pnormal = 0.1643). CONCLUSIONS: Abnormal increases and decreases in the abundances of gut microbiota components, especially Faecalibacterium prausnitzii, were observed in GD patients. TRIAL REGISTRATION: The cross-sectional research was conducted in accordance with the Declaration of Helsinki, and approved by Sir Run Run Shaw Hospital Clinical Trials and Biomedical Ethics Committee. The study has been registered in the Chinese Clinical Trial Registry (ChiCTR1900026164, 24/09/2019, http://www.chictr.org.cn/showproj.aspx?proj=43,455 ).

Gestational diabetes-related gut microbiome dysbiosis is not influenced by different Asian ethnicities and dietary interventions: a pilot study.

Gut microbiome dysbiosis contributes to the pathophysiology of both gestational diabetes mellitus (GDM) and its associated adverse outcomes in the woman and offspring. Even though GDM prevalence, complications, and outcomes vary among different ethnic groups, limited information is available about the influence of ethnicity on gut microbiome dysbiosis in pregnancies complicated by GDM. This pilot prospective cohort study examined the impact of ethnicity on gut dysbiosis in GDM among three Asian ethnic groups (Chinese, Malay, Indian) living in Singapore, and investigated the potential modulatory roles of diet and lifestyle modifications on gut microbiome post-GDM diagnosis. Women with GDM (n = 53) and without GDM (n = 16) were recruited. Fecal samples were collected at 24-28- and 36-40-weeks' gestation and analyzed by targeted 16S rRNA gene-based amplicon sequencing. Permutational multivariate analysis of variance (PERMANOVA) analysis was performed to evaluate differences between groups. Differentially abundant taxa were identified by DeSeq2 based analysis. Functional prediction was performed using the phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt2). Among women with GDM, gut microbiome from different ethnicities harbored common microbial features. However, among those without GDM, there was contrasting microbiome composition between ethnic groups. Microbial members such as Collinsella, Blautia, Ruminococcus, Ruminococcus gnavus, Ruminococcus torques, and Eubacterium hallii groups were differentially enriched (p < 0.05) in women with GDM compared to those without. Among women with GDM, no differences in alpha- and beta- diversity were observed when comparing 24-28 weeks' samples with 36-40 weeks' samples, a period covering intense dietary and lifestyle modification, suggesting an inability to modulate gut microbiota through classic GDM management. Women with GDM have a distinct gut microbiome profile which harbours common features across different Asian ethnic groups, consistent with the notion that specific microbes are involved in the pathogenesis of insulin resistance, pro-inflammatory conditions, and other metabolic dysregulation known to be present in 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.

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.

Association of Gestational Diabetes With the Dynamic Changes of Gut Microbiota in Offspring From 1 to 6 Months of Age.

AIMS: The present study aimed to prospectively evaluate the influence of gestational diabetes mellitus (GDM) on the gut microbiota in 1- and 6-month-old offspring, as well as the dynamic changes from 1 to 6 months of age. METHODS: Seventy-three mother-infant dyads (34 GDM vs 39 non-GDM) were included in this longitudinal study. Two fecal samples were collected for each included infant at home by the parents at 1 month of age ("M1 phase") and again at 6 months of age ("M6 phase"). Gut microbiota were profiled by 16S rRNA gene sequencing. RESULTS: Although no significant differences were observed in diversity and composition between GDM and non-GDM groups in the M1 phase, we observed differential structures and composition in the M6 phase between the 2 groups (P < .05), with lower levels of diversity, 6 depleted and 10 enriched gut microbes among infants born to GDM mothers. The dynamic changes in alpha diversity from the M1 to M6 phase were also significantly different according to GDM status (P < .05). Moreover, we found that the altered gut bacteria in the GDM group were correlated with infants' growth. CONCLUSION: Maternal GDM was associated not only with the community structure and composition in the gut microbiota of offspring at a specific time point, but also with the differential changes from birth to infancy. Altered colonization of the GDM infants' gut microbiota might affect their growth. Our findings underscore the critical impact of GDM on the formation of early-life gut microbiota and on the growth and development of infants.

Integrative metagenomic and metabolomic analyses reveal gut microbiota-derived multiple hits connected to development of gestational diabetes mellitus in humans.

Gestational diabetes mellitus (GDM) is characterized by the development of hyperglycemia and insulin resistance during the second or third trimester of pregnancy, associated with considerable risks to both the mother and developing fetus. Although emerging evidence suggests an association between the altered gut microbiota and GDM, remarkably little is known about the microbial and metabolic mechanisms that link the dysbiosis of the gut microbiota to the development of GDM. In this study, a metagenome-wide association study and serum metabolomics profiling were performed in a cohort of pregnant women with GDM and pregnant women with normal glucose tolerance (NGT). We identified gut microbial alterations associated with GDM and linked to the changes in circulating metabolites. Blood metabolite profiles revealed that GDM patients exhibited a marked increase in 2-hydroxybutyric acid and L-alpha-aminobutyric acid, but a decrease in methionine sulfoxide, allantoin, and dopamine and dopaminergic synapse, when compared with those in NGT controls. Short-chain fatty acid-producing genera, including Faecalibacterium, Prevotella, and Streptococcus, and species Bacteroides coprophilus, Eubacterium siraeum, Faecalibacterium prausnitzii, Prevotella copri, and Prevotella stercorea, were significantly reduced in GDM patients relative to those in NGT controls. Bacterial co-occurrence network analysis revealed that pro-inflammatory bacteria were over-represented as the core species in GDM patients. These microbial and metabolic signatures are closely associated with clinical parameters of glucose metabolism in GDM patients and NGT controls. In conclusion, we identified circulating dopamine insufficiency, imbalanced production of SCFAs, and excessive metabolic inflammation as gut microbiota-driven multiple parallel hits linked to GDM development. This work might explain in part the mechanistic link between altered gut microbiota and GDM pathogenesis, and suggest that gut microbiota may serve as a promising target to intervene in GDM.

Mycobiota composition and changes across pregnancy in patients with gestational diabetes mellitus (GDM).

The gut mycobiota has never been studied either during pregnancy or in patients with gestational diabetes (GDM). This study aimed to analyze the fecal mycobiota of GDM patients during the second (T2) and third (T3) trimester of pregnancy and to compare it with the mycobiota of pregnant normoglycemic women (controls). Forty-one GDM patients and 121 normoglycemic women were studied. GDM mycobiota was composed almost exclusively by the Ascomycota phylum; Basidiomicota accounted for 43% of the relative frequency of the controls. Kluyveromyces (p < 0.001), Metschnikowia (p < 0.001), and Pichia (p < 0.001) showed a significantly higher frequency in GDM patients, while Saccharomyces (p = 0.019), were more prevalent in controls. From T2 to T3, a reduction in fungal alpha diversity was found in GDM patients, with an increase of the relative frequency of Candida, and the reduction of some pro-inflammatory taxa. Many associations between fungi and foods and nutrients were detected. Finally, several fungi and bacteria showed competition or co-occurrence. Patients with GDM showed a predominance of fungal taxa with potential inflammatory effects when compared to normoglycemic pregnant women, with a marked shift in their mycobiota during pregnancy, and complex bacteria-fungi interactions.

Gut microbiota in pregnant Malaysian women: a comparison between trimesters, body mass index and gestational diabetes status.

BACKGROUND: The primary purpose of the study is to determine the variation of gut microbiota composition between first (T1) and third trimester (T3); gestational diabetes mellitus (GDM) and non-gestational diabetes mellitus (NGDM); and also within a different category of Body Mass Index (BMI) of selected pregnant Malaysian women. METHODS: A prospective observational study on selected 38 pregnant Malaysian women attending a tertiary medical centre was carried out. Those with preexisting diabetes, metabolic syndrome or any other endocrine disorders were excluded. GDM was determined using oral glucose tolerance test (OGTT) while BMI was stratified as underweight, normal, pre-obese and obese. Fecal samples were then collected during the first trimester (T1) and the third trimester (T3). The V3-V4 region of 16S rRNA gene amplicon libraries were sequenced and analyzed using QIIME (version 1.9.1) and METAGENassist. RESULTS: Twelve women (31.6%) were diagnosed as GDM. A trend of lower α-diversity indices in GDM, pre-obese and obese pregnant women were observed. Partial Least Squares Discriminant Analysis (PLS-DA) shows a clustering of gut microbiota according to GDM status and BMI, but not by trimester. Genera Acidaminococcus, Clostridium, Megasphaera and Allisonella were higher, and Barnesiella and Blautia were lower in GDM group (P < 0.005). Obese patients had gut microbiota that was enriched with bacteria of Negativicutes and Proteobacteria class such as Megamonas, Succinatimonas and Dialister (P < 0.005). The normal and mild underweight profiles on the other hand had a higher bacteria from the class of Clostridia (Papillibacter, Oscillibacter, Oscillospira, Blautia, Dorea) and Bacteroidia (Alistipes, Prevotella, Paraprevotella) (P < 0.005). CONCLUSION: The prevalence and variation of several key bacteria from classes of Negativicutes, Clostridia and Proteobacteria has potential metabolic links with GDM and body weight during pregnancy which require further functional validation.