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

Intrauterine Shaping of Fetal Microbiota

Mechanisms resulting from the physiological immaturity of the digestive system in children delivered before 32 weeks of gestation and, in particular, different interactions between the microbiome and the body have not been fully elucidated yet. Next-generation sequencing methods demonstrated the presence of bacterial DNA in the placenta and amniotic fluid, which may reflect bacterial populations that initiate intestinal colonization in utero. Numerous studies confirmed the hypothesis stating that intestinal bacteria played an important role in the pathogenesis of necrotizing enterocolitis (NEC) early- and late-onset neonatal sepsis (EONS and LONS). The model and scale of disorders within the intestinal microbiome are the subject of active research in premature infants. Neonatal meconium was primarily used as an indicator defining the environment in utero, as it is formed before birth. Metagenomic results and previous data from microbiological bacterial cultures showed a correlation between the time from birth to sample collection and the detection of bacteria in the neonatal meconium. Therefore, it may be determined that the colonization of the newborn's intestines is influenced by numerous factors, which may be divided into prenatal, perinatal, and postnatal, with particular emphasis put on the mode of delivery and contact with the parent immediately after birth. Background: The aim of this review was to collect available data on the intrauterine shaping of the fetal microbiota. Methods: On 13 March 2024, the available literature in the PubMed National Library of Medicine search engine was reviewed using the following selected keywords: "placental microbiome", "intestinal bacteria in newborns and premature infants", and "intrauterine microbiota". Results: After reviewing the available articles and abstracts and an in-depth analysis of their content, over 100 articles were selected for detailed elaboration. We focused on the origin of microorganisms shaping the microbiota of newborns. We also described the types of bacteria that made up the intrauterine microbiota and the intestinal microbiota of newborns. Conclusions: The data presented in the review on the microbiome of both term newborns and those with a body weight below 1200 g indicate a possible intrauterine colonization of the fetus depending on the duration of pregnancy. The colonization occurs both via the vaginal and intestinal route (hematogenous route). However, there are differences in the demonstrated representatives of various types of bacteria, phyla Firmicutes and Actinobacteria in particular, taking account of the distribution in their abundance in the individual groups of pregnancy duration. Simultaneously, the distribution of the phyla Actinobacteria and Proteobacteria is consistent. Considering the duration of pregnancy, it may also be concluded that the bacterial flora of vaginal origin dominates in preterm newborns, while the flora of intestinal origin dominates in term newborns. This might explain the role of bacterial and infectious factors in inducing premature birth with the rupture of fetal membranes.

The effects of probiotics administration during pregnancy on preeclampsia and associated maternal, fetal, and newborn outcomes: a systematic review and meta-analysis

OBJECTIVE

This study aimed to synthesize the available evidence on probiotic administration during pregnancy for the prevention of preeclampsia and its effects on related maternal, fetal, and newborn outcomes.

DATA SOURCES

Six databases were systematically searched for eligible studies, namely Ovid MEDLINE, Embase, CINAHL, Cochrane, Global Index Medicus, and the Maternity and Infant Care Database, from inception to August 2, 2023.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials that evaluated the effects of probiotic administration on women during any stage of pregnancy were eligible for inclusion.

METHODS

The protocol was registered with the International Prospective Register of Systematic Reviews under identifier CRD42023421613. Evaluating study eligibility, extracting data, assessing risk of bias (ROB-2 tool), and rating certainty (Grading of Recommendations, Assessment, Development and Evaluations) were conducted independently by 2 authors. The primary outcomes were incidence of preeclampsia, eclampsia, and maternal mortality. A meta-analysis was performed, and the results were reported as risk ratios with 95% confidence intervals.

RESULTS

A total of 29 trials (7735 pregnant women) met the eligibility criteria. There was heterogeneity across the trials in the population of enrolled women and the type of probiotic tested (20 different strains), although most used oral administration. Probiotics may make no difference to the risk of preeclampsia (risk ratio, 1.14; 95% confidence interval, 0.84-1.53; 11 trials; 2401 women; low certainty evidence), preterm birth at <37 weeks' gestation (risk ratio, 0.93; 95% confidence interval, 0.66-1.30; 18 trials, 4016 women; low certainty evidence), or gestational age at delivery (mean difference, -0.03 weeks [≈0.2 days]; 95% confidence interval, -0.16 to 0.10 weeks [≈ -1.1 to 0.7 days]; 13 trials, 2194 women; low certainty evidence). It is difficult to assess the effects of probiotics on other secondary outcomes because the evidence was of very low certainty, however, no benefits or harms were observed.

CONCLUSION

Limited evidence suggests that probiotic supplementation does not affect the risk for preeclampsia. Further high-quality trials are needed to definitively assess the benefits and possible harms of probiotic supplementation during pregnancy. There is also a lack of data from trials that included women who were undernourished or who experienced microbial dysbiosis and for whom probiotic supplementation might be useful.

Maternal Gestational Diabetes Is Associated with High Risk of Childhood Overweight and Obesity: A Cross-Sectional Study in Pre-School Children Aged 2–5 Years

Background and Objectives: Childhood obesity is a global public health concern with long-term and serious health implications. An important factor for childhood obesity is maternal gestational diabetes mellitus (GDM), which in turn impacts maternal and offspring long-term health. This study aimed to investigate the associations between maternal GDM and childhood weight status and multiple anthropometric and sociodemographic factors and perinatal outcomes. Materials and Methods: A total of 5348 children aged 2–5 years old and their paired mothers took part in the study. Questionnaires were utilized to evaluate the sociodemographic factors and perinatal outcomes as well as smoking habits, educational level, economic status, age, and parity status. Children’s anthropometric parameters were measured, and maternal medical history, preterm birth records, and anthropometric measures during pregnancy were retrieved by their medical records. Results: Overall, 16.4% of the children aged at 2–5 years were overweight, and 8.2% of them were affected by obesity, leading to a total 24.6% of children with overweight/obesity. Further, 5.5% of the enrolled mothers were diagnosed with gestational diabetes mellitus. GDM doubles the probability of childhood overweight/obesity at ages 2–5 years old independently of multiple confounding factors. Pre-pregnancy overweight and obesity, older maternal age, and smoking are risk factors for GDM, while GDM additionally increases the risk of preterm birth. Children of mothers that developed GDM were at greater risk of overweight or obesity, with the association between GDM and offspring’s weight status being independent of confounding factors. Conclusions: GDM is a severe public health issue with prolonged complications for both the mother and their children. Public health approaches and programs need to promote the negative role of pre-pregnancy weight and smoking status as well as the significance of a good glycemic control throughout gestation in women of childbearing age.

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

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

Oral bacteria, oral health, and adverse pregnancy outcomes

The link between oral health and adverse pregnancy outcomes has been suggested by numerous epidemiological studies. More recent studies indicate the relationship between severity of periodontal disease and adverse pregnancy outcomes. Two virulence mechanisms are proposed: direct invasion of oral microorganisms or their components into the fetal-placenta unit and inflammatory mediators produced in the oral cavity affecting the fetal-placenta unit. While interventional periodontal therapy still yielded contradictory results, animal studies suggest that maternal supplementation of omega-3 fatty acids protects the fetus by suppressing inflammation as well as bacteria proliferation in the placenta. This article reviews the recent epidemiological, mechanistic, interventional, and therapeutic studies of oral health and adverse pregnancy outcomes.

Effects of enriched seafood sticks (heat-inactivated B. animalis subsp. lactis CECT 8145, inulin, omega-3) on cardiometabolic risk factors and gut microbiota in abdominally obese subjects: randomized controlled trial

PURPOSE

To assess the effects of enriched seafood sticks with postbiotic and bioactive compounds on CMD risk factors and the gut microbiota in abdominally obese individuals.

METHODS

Randomized, double-blind, parallel, placebo-controlled trial with abdominally obese individuals. Participants (n = 120) consumed 50 g/day of enriched seafood sticks containing SIAP: (10¹⁰ colony forming units (CFUs) of heat-inactivated B. animalis subsp. lactis CECT8145, 370 mg/day omega 3 and 1.7 g/day inulin), or 50 g/day of placebo seafood sticks for 12 weeks. At 12 weeks, an acute single-dose study of 4 h was performed.

RESULTS

Sustained SIAP2 consumption significantly decreased the insulin by - 5.25 mg/dL and HOMA-IR (homeostatic Model Assessment of Insulin Resistance) by - 1.33. In women, SIAP2 consumption significantly decreased the pulse pressure (PP) by - 4.69 mmHg. Gut microbiota analysis showed a negative association between glycemic parameter reduction and Alistipes finegoldii and Ruminococcaceae, and between PP reduction and Prevotella 9-ASV0283 and Christensenellaceae. In the acute single dose-study 4-h, SIAP2 consumption produced a lower increase in the postprandial circulating triglyceride levels [23.9 (7.03) mg/dL (mean [standard error])] than the observed with placebo [49.0 (9.52)] mg/dL.

CONCLUSION

In abdominally obese individuals, enriched seafood sticks induce a potential protection against type 2 diabetes development by the reduction in the insulin and HOMA-IR; and in cardiovascular disease, in women, by the PP reduction. These effects are accompanied by partial changes in the gut microbiota composition. The enriched seafood sticks reduce the atherogenic triglyceride postprandial concentrations. Our results support the use of enriched seafood sticks as a complementary strategy in the management of CMD risk factors. REGISTRATION NUMBER OF CLINICAL TRIAL: ( www.

CLINICALTRIALS

gov ): NCT03630588 (August 15, 2018).

Can Lactobacillus spp. Be a Factor Reducing the Risk of Miscarriage?

Pregnancy loss is a common obstetric problem. Significant causes of miscarriage include genetic and epigenetic disorders of the embryo, immunological and endocrine factors, uterine malformations, improper embryo selection, and lifestyle. Perhaps a hitherto underappreciated cause of miscarriage may be an abnormal microbiota composition of the female reproductive system. Lactobacillus spp. is the most common bacteria within the reproductive tract. However, the protective role of Lactobacilli in the vagina has been well described in the literature, while it is still unknown what function Lactobacilli may have in the uterus. Moreover, new research shows that Lactobacillus spp. can have a role in miscarriage. However, both molecular and immunological mechanisms of host-Lactobacillus spp. interactions are not fully understood. Understanding these relationships will help address the importance and extent of the protective role of Lactobacillus spp. in miscarriage.

Focus on the Gut-Kidney Axis in Health and Disease

The recent new developments in technology with culture-independent techniques including genome sequencing methodologies shed light on the identification of microbiota bacterial species and their role in health and disease. Microbiome is actually reported as an important predictive tool for evaluating characteristic shifts in case of disease. Our present review states the development of different renal diseases and pathologies linked to the intestinal dysbiosis, which impacts on host homeostasis. The gastrointestinal-kidney dialogue provides intriguing features in the pathogenesis of several renal diseases. Without any doubt, investigation of this interconnection consists one of the most cutting-edge areas of research with potential implications on our health.

The Impact of the One-Day Clinic Diabetes Mellitus Management Model on Perinatal Outcomes in Patients with Gestational Diabetes Mellitus

OBJECTIVE

The aim of the present study was to explore the impact of the one-day clinic diabetes mellitus (DM) management model on perinatal outcomes in patients with gestational diabetes mellitus (GDM).

METHODS

A total of 995 patients who underwent prenatal checkups at our hospital and were diagnosed with GDM by oral glucose tolerance test (OGTT) screening at 24-28 weeks of gestational age were enrolled between December 2018 and August 2020. The patients were randomly divided into a study group (541 cases) and a control group (454 cases). One-day clinic intervention for DM was conducted in the study group, while individualized dietary interventions and exercise instruction were given in the control group. The perinatal outcomes of patients were compared between the two groups.

RESULTS

In the study group, maternal weight gain, fasting blood glucose before delivery, the incidence of abnormality in postpartum OGTT, and abnormality of pancreatic islet function were lower than in the control group, and the differences were statistically significant (P < 0.05). The percentage of patients with insulin treatment in the study group was higher than in the control group, and the difference was statistically significant (P < 0.05). The incidence of premature rupture of membranes, macrosomia, and neonatal jaundice was lower in the study group than in the control group, and the differences were statistically significant (P < 0.05).

CONCLUSION

The one-day clinic DM management model can effectively control weight gain and blood glucose levels during pregnancy in patients with GDM, resulting in a higher recovery rate of blood glucose and islet function after delivery and a lower incidence of premature rupture of membranes, macrosomia, and neonatal jaundice. The one-day clinic DM management model could therefore have profound implications for reducing and delaying the onset of postpartum type 2 diabetes in patients with GDM.

Gestational Diabetes Mellitus: A Harbinger of the Vicious Cycle of Diabetes

Gestational diabetes mellitus (GDM), characterized by a transitory form of diabetes induced by insulin resistance and pancreatic β-cell dysfunction during pregnancy, has been identified as one of the major obstacles in achieving improved maternal and child health. Approximately 9-25% of pregnancies worldwide are impacted by the acute, long-term, and transgenerational health complications of this disease. Here, we discuss how GDM affects longstanding maternal and neonatal outcomes, as well as health risks that likely persist into future generations. In addition to the current challenges in the management and diagnosis of and the complications associated with GDM, we discuss current preclinical models of GDM to better understand the underlying pathophysiology of the disease and the timely need to increase our scientific toolbox to identify strategies to prevent and treat GDM, thereby advancing clinical care.

Pre-Eclampsia: Microbiota possibly playing a role

Pre-eclampsia (PE) is a complication of pregnancy that is associated with mortality and morbidity in mothers and fetuses worldwide. Oxygen dysregulation in the placenta, abnormal remodeling of the spiral artery, defective placentation, oxidative stress at the fetal-maternal border, inflammation and angiogenic impairment in the maternal circulation are the main causes of this syndrome. These events result in a systemic and diffuse endothelial cell dysfunction, an essential pathophysiological feature of PE. The impact of bacteria on the multifactorial pathway of PE is the recent focus of scientific inquiry since microbes may cause each of the aforementioned features. Microbes and their derivatives by producing antigens and other inflammatory factors may trigger infection and inflammatory responses. A mother's bacterial communities in the oral cavity, gut, vagina, cervix and uterine along with the placenta and amniotic fluid microbiota may be involved in the development of PE. Here, we review the mechanistic and pathogenic role of bacteria in the development of PE. Then, we highlight the impact of alterations in a set of maternal microbiota (dysbiosis) on the pathogenesis of PE.

Immunological Role of the Maternal Uterine Microbiome in Pregnancy: Pregnancies Pathologies and Alterated Microbiota

Understanding what happens at the time of embryo implantation has been the subject of significant research. Investigators from many differing fields including maternal fetal medicine, microbiology, genetics, reproductive endocrinology and immunology have all been studying the moment the embryo interacts with the maternal endometrium. A perfect relationship between the uterus and the embryo, mediated by a tightly controlled interaction between the embryo and the endometrium, is required for successful implantation. Any factors affecting this communication, such as altered microbiome may lead to poor reproductive outcomes. Current theories suggest that altered microbiota may trigger an inflammatory response in the endometrium that affects the success of embryo implantation, as inflammatory mediators are tightly regulated during the adhesion of the blastocyst to the epithelial endometrial wall. In this review, we will highlight the various microbiome found during the periconceptual period, the microbiomes interaction with immunological responses surrounding the time of implantation, its effect on implantation, placentation and ultimately maternal and neonatal outcomes.

Prevention of Gestational Diabetes Mellitus (GDM) and Probiotics: Mechanism of Action: A Review

BACKGROUND

Gestational Diabetes Mellitus (GDM) is a health problem that is increasing around the world.

INTRODUCTION

Prevention of GDM, rather than treatment, could have several benefits in terms of both health and economic cost. Even a slight reduction in maternal glucose in non-diabetic women, particularly in women at high risk for GDM, may have significant benefits for pregnancy results and the future health of off-springs. Probiotics are a relatively new intervention, which are assessed by mothers' metabolism, and can reduce blood sugar levels, prevent gestational diabetes and reduce the maternal and fetal complications resulting from it. The aim of this study was to review the studies on the prevention of gestational diabetes and assess the potential beneficial effects of probiotics on gestational diabetes and their possible mechanism of action.

METHODS

Articles compiled through clinical trials indexed in PubMed, Science Direct, Cochran, and Medlib between 2000 and 2017, with the keywords probiotics, prevention, and gestational diabetes mellitus were selected.

RESULTS

Considering the potential of probiotics in the modulation of gut microbiota, naturalization increases intestinal permeability, regulation of pro-inflammatory mediators' secretion and thereby controlling local and systemic inflammation results in decreasing intestinal permeability, enhancing the immune system. It likely has the ability to prevent or control diabetes during pregnancy although confirmatory studies are still needed.

CONCLUSION

Experimental and clinical evidence support the supposition that the modulation of the gut microbiota via probiotic microorganisms could be effective in the prevention of gestational diabetes mellitus.

Laboratory Analysis Techniques for the Perinatal Microbiome: Implications for Studies of Probiotic Interventions

The microbiome is composed of many organisms and is impacted by an intricate exchange between genetics and environmental factors. The perinatal microbiome influences both the developing fetus and the pregnant person. The purpose of this article is to describe the tests that are currently available for laboratory analysis of the perinatal microbiome in relationship to probiotic interventions. This article focuses on the bacterial component of the microbiome. Although adverse outcomes associated with the perinatal microbiome have been studied, a comprehensive understanding of the physiologic perinatal microbiome is still emerging. Early efforts to influence the perinatal microbiome through probiotics are currently under investigation. Unique terminology is defined, and the microbial composition of perinatal microbiota is summarized. The outcomes of studies of antenatal probiotics are summarized. Microbiome testing and analysis are defined and compared. Implications for perinatal care and probiotics research are presented.