Diabetes Mellitus, Obesity, and the Placenta

Pathophysiology from preconception, during pregnancy, and beyond

Gestational diabetes is the most common medical complication in pregnancy. Historically, gestational diabetes was considered a pregnancy complication involving treatment of rising glycaemia late in the second trimester. However, recent evidence challenges this view. Pre-pregnancy and pregnancy-specific factors influence gestational glycaemia, with open questions regarding roles of non-glycaemic factors in the aetiology and consequences of gestational diabetes. Varying patterns of insulin secretion and resistance in early and late pregnancy underlie a heterogeneity of gestational diabetes in the timing and pathophysiological subtypes with clinical implications: early gestational diabetes and insulin resistant gestational diabetes subtypes are associated with a higher risk of pregnancy complications. Metabolic perturbations of early gestational diabetes can affect early placental development, affecting maternal metabolism and fetal development. Fetal hyperinsulinaemia can affect the development of multiple fetal tissues, with short-term and long-term consequences. Pregnancy complications are prevented by managing glycaemia in early and late pregnancy in some, but not all women with gestational diabetes. A better understanding of the pathophysiology and heterogeneity of gestational diabetes will help to develop novel management approaches with focus on improved prevention of maternal and offspring short-term and long-term complications, from pre-conception, throughout pregnancy, and beyond.

Placental pathology and fetal growth outcomes in pregnancies complicated by maternal obesity

BACKGROUND

The rising prevalence of maternal obesity presents a significant health concern because of the possible implications for obstetric complications and neonatal outcomes. Understanding the impact of obesity on placental structure and function as well as fetal growth and infant outcomes is important to improve the care of these potentially high-risk pregnancies. This study aimed to determine the effect of elevated maternal BMI on histopathologic patterns of placental injury and its consequences on fetal growth.

METHODS

Data were collected from an ongoing cohort of maternal-infant dyads in the UCSD Obstetric Registry spanning 2011-2020. Maternal characteristics, including BMI, hypertensive disease and diabetes, placental gross and histopathology, and infant characteristics, including sex and birthweight, were recorded and analyzed. ANOVA and chi-square tests were used in initial analyses, followed by log-binomial and linear regression models adjusted for relevant confounders to determine associations between maternal BMI, specific patterns of placental injury, and infant birthweight percentiles.

RESULTS

Among 1366 maternal-infant dyads, placentas from mothers with overweight and obesity were heavier and demonstrated higher adjusted relative risks of chronic villitis (CV), decidual vasculopathy, intervillous thrombosis, and normoblastemia. Placental efficiency, determined by fetal-placental weight ratio, was decreased with increasing BMI. Maternal obesity was associated with higher rates of preterm birth and higher birthweight percentiles. Multiple placental lesions, including maternal (MVM) and fetal vascular malperfusion (FVM), exhibited significant effects on birthweight percentiles; however, only MVM showed a differential effect based on maternal obesity.

CONCLUSIONS

Presence of obesity in pregnancy is associated with increased rates of placental patterns of injury, decreased placental efficiency, and increased birthweight percentiles. While placental lesions, such as CV, have the potential to negatively impact fetal growth, the resulting birthweight percentiles demonstrate a more complex relationship between maternal obesity and fetal growth, that likely involves placental and fetal adaptation to the altered in utero environment.

The application of plasma circRAD18 in the prediction of gestational diabetes mellitus (GDM) and its adverse effects

BACKGROUND

In cancer biology, circRAD18 promotes glucose metabolism, potentially indicating its involvement in glucose metabolism-related disorders, such as gestational diabetes mellitus (GDM). The present study investigated the predictive role of circRAD18 in GDM and its potential adverse effects.

METHODS

A total of 482 women who intended to get pregnant in short-term were enrolled. For those who successfully conceived, plasma samples were collected and followed up until delivery to monitor the occurrence of GDM and its associated adverse events. The accumulation of circRAD18 in plasma was analyzed using RT-qPCR. GDM-free curves and ROC curves were plotted to assess the predictive value of plasma circRAD18 for GDM.

RESULTS

After admitting 482 female patients, 388 of them achieved pregnancy within half a year. During the follow-up period, 52 cases were diagnosed with GDM. Compared to non-GDM group (n = 336), the GDM group (n = 52) had a lower accumulation level of circRAD18 on the day of pregnancy confirmation. In addition, low levels of circRAD18 accumulation on that day distinguished potential GDM patients from non-GDM cases. The 388 cases were divided into high and low circRAD18 level groups (n = 194). GDM-free curve analysis showed that patients in the low circRAD18 level group had a higher incidence of GDM compared to the high level group (43/194 vs. 9/194). A close association was found between low levels of plasma circRAD18 and hypertension, but not premature delivery, intrauterine death, malformation, intrauterine infection, miscarriage, macrosomia or intrauterine distress.

CONCLUSION

The reduction in the accumulation of plasma circRAD18 is predictive of GDM and hypertension in pregnant women.

Extracellular vesicle-mediated targeting strategies for long-term health benefits in gestational diabetes

Extracellular vesicles (EVs) are critical mediators of cell communication, playing important roles in regulating molecular cross-talk between different metabolic tissues and influencing insulin sensitivity in both healthy and gestational diabetes mellitus (GDM) pregnancies. The ability of EVs to transfer molecular cargo between cells imbues them with potential as therapeutic agents. During pregnancy, the placenta assumes a vital role in metabolic regulation, with multiple mechanisms of placenta-mediated EV cross-talk serving as central components in GDM pathophysiology. This review focuses on the role of the placenta in the pathophysiology of GDM and explores the possibilities and prospects of targeting the placenta to address insulin resistance and placental dysfunction in GDM. Additionally, we propose the use of EVs as a novel method for targeted therapeutics in treating the dysfunctional placenta. The primary aim of this review is to comprehend the current status of EV targeting approaches and assess the potential application of these strategies in placental therapeutics, thereby delivering molecular cargo and improving maternal and fetal outcomes in GDM. We propose that EVs have the potential to revolutionize GDM management, offering hope for enhanced maternal-fetal health outcomes and more effective treatments.

The Role of Annexin A1 in DNA Damage Response in Placental Cells: Impact on Gestational Diabetes Mellitus

The functions of annexin A1 (ANXA1), which is expressed on membranes and in cytoplasmic granules, have been fully described. Nonetheless, the role of this protein in protecting against DNA damage in the nucleus is still emerging and requires further investigation. Here, we investigated the involvement of ANXA1 in the DNA damage response in placental cells. Placenta was collected from ANXA1 knockout mice (AnxA1^-/-) and pregnant women with gestational diabetes mellitus (GDM). The placental morphology and ANXA1 expression, which are related to the modulation of cellular response markers in the presence of DNA damage, were analyzed. The total area of AnxA1^-/- placenta was smaller due to a reduced labyrinth zone, enhanced DNA damage, and impaired base excision repair (BER) enzymes, which resulted in the induction of apoptosis in the labyrinthine and junctional layers. The placentas of pregnant women with GDM showed reduced expression of AnxA1 in the villous compartment, increased DNA damage, apoptosis, and a reduction of enzymes involved in the BER pathway. Our translational data provide valuable insights into the possible involvement of ANXA1 in the response of placental cells to oxidative DNA damage and represent an advancement in investigations into the mechanisms involved in placental biology.

The impact of polycystic ovary syndrome on placental histopathology patterns in in-vitro fertilization singleton live births

INTRODUCTION

Pregnant polycystic ovary syndrome (PCOS) patients are at increased risk for myriad obstetric complications, with the placenta thought to play a key role in their development. We aimed to evaluate placental histopathology patterns in placentas of women with PCOS who underwent in-vitro-fertilization (IVF).

METHODS

This retrospective study utilized full gross and histopathologic assessment of placentas of all women who had IVF treatment and delivered at the Royal Victoria Hospital from 2009 to 2017, regardless of complications or mode of delivery. Pathologic findings included anatomic, inflammation, villous maturation, and vascular mal-perfusion features. Placentas of PCOS women were compared to those of ovulatory controls. Multivariate logistic regression was used to adjust results for confounding factors potentially associated with significant placental and perinatal characteristics.

RESULTS

Women with PCOS (n = 47) were more likely to develop gestational diabetes mellitus compared to ovulatory controls (n = 1121) (38.3% vs. 9.8%, p < 0.001). Placentas from PCOS women were more likely circumvallate placentas (aOR 8.3, 95%CI 1.9-37.3) and more likely to have a hypercoiled umbilical cord (aOR 6.8 95%CI 1.3-36.8) and villitis of unknown etiology (aOR 6.1, 95%CI 1.5-25.6). There was an increased likelihood of chorangiosis (aOR 2.7, 95% CI 1.3-5.8), evidence of fetal vascular malperfusion based on one criteria (aOR 2.7, 95%CI 1.1-7.4), or more than one criteria (aOR 6.4, 95%CI 1.6-25.9), more nucleated fetal red blood cells (aOR 5.2, 95%CI 1.1-24.5), and a higher likelihood of chorangiomas (aOR 9.4, 95%CI 1.6-55.1) in placentas from PCOS women than in controls.

DISCUSSION

IVF pregnancies' placental histopathological characteristics are significantly impacted by an underlying diagnosis of PCOS, including important anatomic changes and vascular placental abnormalities.

Biomarkers of oxidative stress and reproductive complications

Oxidative stress is the result of an imbalance between the formation of reactive oxygen species (ROS) and the levels of enzymatic and non-enzymatic antioxidants. The assessment of biological redox status is performed by the use of oxidative stress biomarkers. An oxidative stress biomarker is defined as any physical structure or process or chemical compound that can be assessed in a living being (in vivo) or in solid or fluid parts thereof (in vitro), the determination of which is a reproducible and reliable indicator of oxidative stress. The use of oxidative stress biomarkers allows early identification of the risk of developing diseases associated with this process and also opens up possibilities for new treatments. At the end of the last century, interest in oxidative stress biomarkers began to grow, due to evidence of the association between the generation of free radicals and various pathologies. Up to now, a significant number of studies have been carried out to identify and apply different oxidative stress biomarkers in clinical practice. Among the most important oxidative stress biomarkers, it can be mentioned the products of oxidative modifications of lipids, proteins, nucleic acids, and uric acid as well as the measurement of the total antioxidant capacity of fluids in the human body. In this review, we aim to present recent advances and current knowledge on the main biomarkers of oxidative stress, including the discovery of new biomarkers, with emphasis on the various reproductive complications associated with variations in oxidative stress levels.

Associations between maternal dietary scores during early pregnancy with placental outcomes

Background and aims

Individual macronutrient and micronutrient effects on placental growth have been widely investigated. However, the influence of overall maternal diet is relatively unknown. Therefore, the aim of this study is to examine associations between a range of maternal dietary scores during early pregnancy with placental outcomes, and to investigate whether there is evidence of sexual dimorphism.

Methods

This analysis of the Lifeways Cross-Generational Cohort includes 276 mother-child pairs. A validated 148-item semi-quantitative food frequency questionnaire assessed maternal diet in early pregnancy. Dietary scores reflecting dietary quality [Healthy Eating Index (HEI-2015), Dietary Approaches to Stop Hypertension (DASH)], dietary inflammatory potential [Dietary Inflammatory Index (DII) and the energy adjusted DII (E-DII)], dietary antioxidant status [Dietary Antioxidant Quality (DAQ)], and glycemic and insulinemic loads/indices (GL/GI, IL/II) were calculated. Linear regression analyses assessed maternal dietary score relationships with untrimmed placental weight (PW) and birth weight:placental weight (BW:PW) ratio.

Results

In fully adjusted models, maternal E-DII and GI were positively associated, and HEI-2015 and DAQ were negatively associated with PW (B: 12.31, 95% CI: 0.41, 24.20, p = 0.04, B: 4.13, 95% CI: 0.10, 8.17, p = 0.04, B: -2.70, 95% CI: -5.03, -0.35, p = 0.02 and B: -15.03, 95% CI: -28.08, -1.98, p = 0.02, for E-DII, GI, HEI-2015 and DAQ respectively). Maternal DAQ associations with BW:PW ratio were attenuated. When stratified by sex, maternal GI and pregnancy-specific DAQ were associated with PW in female offspring (B: 5.61, 95% CI: 0.27, 10.96, p = 0.04 and B: -15.31, 95% CI: -30.35, -0.27, p = 0.046). Maternal E-DII and HEI-2015 were associated with PW in males (B: 24.31, 95% CI: 5.66, 42.96, p = 0.01 and B: -3.85, 95% CI: -7.47, -0.35, p = 0.03 respectively).

Conclusion

The results of this novel investigation suggest that maternal diet may influence placental development. Female fetuses may be more sensitive to increased glucose levels whereas male fetuses may be more susceptible to in-utero stresses that are regulated by inflammatory pathways and overall diet quality. Hence, early pregnancy offers an opportune time for a mother to prioritize dietary changes that focus on reducing inflammatory and glycemic responses.

Placental Transcriptome Profiling in Subtypes of Diabetic Pregnancies Is Strongly Confounded by Fetal Sex

The placenta is a temporary organ with a unique structure and function to ensure healthy fetal development. Placental dysfunction is involved in pre-eclampsia (PE), fetal growth restriction, preterm birth, and gestational diabetes mellitus (GDM). A diabetic state affects maternal and fetal health and may lead to functional alterations of placental metabolism, inflammation, hypoxia, and weight, amplifying the fetal stress. The placental molecular adaptations to the diabetic environment and the adaptive spatio-temporal consequences to elevated glucose or insulin are largely unknown (2). We aimed to identify gene expression signatures related to the diabetic placental pathology of placentas from women with diabetes mellitus. Human placenta samples (n = 77) consisting of healthy controls, women with either gestational diabetes mellitus (GDM), type 1 or type 2 diabetes, and women with GDM, type 1 or type 2 diabetes and superimposed PE were collected. Interestingly, gene expression differences quantified by total RNA sequencing were mainly driven by fetal sex rather than clinical diagnosis. Association of the principal components with a full set of clinical patient data identified fetal sex as the single main explanatory variable. Accordingly, placentas complicated by type 1 and type 2 diabetes showed only few differentially expressed genes, while possible effects of GDM and diabetic pregnancy complicated by PE were not identifiable in this cohort. We conclude that fetal sex has a prominent effect on the placental transcriptome, dominating and confounding gene expression signatures resulting from diabetes mellitus in settings of well-controlled diabetic disease. Our results support the notion of placenta as a sexual dimorphic organ.

Placental abnormalities in type 1 and type 2 diabetes mellitus: a systematic review and metaanalysis of shear wave elastography

OBJECTIVE

This study aimed to describe the placental changes occurring in women with preexisting diabetes mellitus and to determine if elastography can detect placental changes in vivo.

DATA SOURCES

PubMed, Embase, Medline, and Cochrane were searched to identify English language studies published until July 2020.

STUDY ELIGIBILITY CRITERIA

1) For key question 1, studies that described histopathologic changes in placentas from women with known diabetes mellitus and 2) for key question 2, those that described structural-placental changes detectable by elastography in high-risk pregnancies (eg, those complicated by preeclampsia and/or fetal growth restriction), were included.

METHODS

For key question 1, we grouped placental pathologies using the Amsterdam International Consensus Group definitions. For key question 2, we conducted a metaanalysis including all data from studies reporting placental stiffness in meters per second (m/s) or kilopascals (kPa). The mean difference (95% confidence interval) was calculated using a random effects model.

RESULTS

Data were extracted from 14 studies of placental histopathology in women with known diabetes. In this group, a wide variety of placental histopathologic changes are described, though none are considered pathognomonic. The histopathologic changes including maternal vascular malperfusion, fetal vascular malperfusion, and/or infectious/inflammatory/other changes were divided into 3 broad categories on the basis of presumed etiology. A total of 15 studies reported the placental stiffness scores in women with a high-risk pregnancy vs those with a normal pregnancy. Only 1 reported stiffness scores for placentas in women with preexisting diabetes mellitus (N<10 women). Pooled analysis of 14 studies with available data included 478 "high-risk pregnancies" and 828 control or healthy pregnancies. Maternal-derived pathologies resulted in higher placental stiffness (mean difference 4.5 kPa [95% confidence interval, 3.16-5.87]) compared with control or healthy pregnancies. Fetal-derived pathologies also resulted in higher placental stiffness (mean difference of 6.5 kPa [95% confidence interval, 1.08-11.86]) compared with control or healthy pregnancies.

CONCLUSION

Shear wave elastography may provide an in vivo approximation of placental histopathology in women with certain kinds of high-risk pregnancies. A high-risk pregnancy may involve maternal- and fetal-derived pathologies. Further studies, particularly in women with preexisting diabetes, are needed to confirm this observation.

Placental DNA Methylation in pregnancies complicated by maternal diabetes and/or obesity: State of the Art and research gaps

SUMMARYMaternal diabetes and/or obesity in pregnancy are undoubtedly associated with later disease-risk in the offspring. The placenta, interposed between the mother and the fetus, is a potential mediator of this risk through epigenetic mechanisms, including DNA methylation. In recent years, multiple studies have identified differentially methylated CpG sites in the placental tissue DNA in pregnancies complicated by diabetes and obesity. We reviewed all published original research relevant to this topic and analyzed our findings with the focus of identifying overlaps, contradictions and gaps. Most studies focused on the association of gestational diabetes and/or hyperglycemia in pregnancy and DNA methylation in placental tissue at term. We identified overlaps in results related to specific candidate genes, but also observed a large research gap of pregnancies affected by type 1 diabetes. Other unanswered questions relate to analysis of specific placental cell types and the timing of DNA methylation change in response to diabetes and obesity during pregnancy. Maternal metabolism is altered already in the first trimester involving structural and functional changes in the placenta, but studies into its effects on placental DNA methylation during this period are lacking and urgently needed. Fetal sex is also an important determinant of pregnancy outcome, but only few studies have taken this into account. Collectively, we provide a reference work for researchers working in this large and evolving field. Based on the results of the literature review, we formulate suggestions for future focus of placental DNA methylation studies in pregnancies complicated by diabetes and obesity.

Type 1 Diabetes Mellitus and the First Trimester Placenta: Hyperglycemia-Induced Effects on Trophoblast Proliferation, Cell Cycle Regulators, and Invasion

Type 1 diabetes mellitus (T1DM) is associated with reduced fetal growth in early pregnancy, but a contributing role of the placenta has remained elusive. Thus, we investigated whether T1DM alters placental development in the first trimester. Using a protein array, the level of 60 cell-cycle-related proteins was determined in human first trimester placental tissue (gestational week 5–11) from control (n = 11) and T1DM pregnancies (n = 12). Primary trophoblasts (gestational week 7–12, n = 32) were incubated in the absence (control) or presence of hyperglycemia (25 mM D-glucose) and hyperosmolarity (5.5 mM D-glucose + 19.5 mM D-mannitol). We quantified the number of viable and dead trophoblasts (CASY Counter) and assessed cell cycle distribution (FACS) and trophoblast invasion using a transwell assay. T1DM was associated with a significant (p < 0.05) downregulation of Ki67 (−26%), chk1 (−25%), and p73 (−26%). The number of viable trophoblasts was reduced under hyperglycemia (−23%) and hyperosmolarity (−18%), whereas trophoblast invasion was increased only under hyperglycemia (+6%). Trophoblast cell death and cell cycle distribution remained unaffected. Collectively, our data demonstrate that hyperglycemia decreases trophoblast proliferation as a potential contributing factor to the reduced placental growth in T1DM in vivo.

Maternal Dietary Quality and Dietary Inflammation Associations with Offspring Growth, Placental Development, and DNA Methylation

The ‘Developmental Origins of Health and Diseases’ hypothesis posits that prenatal maternal diet influences offspring growth and later life health outcomes. Dietary assessment has focused on selected nutrients. However, this approach does not consider the complex interactions between foods and nutrients. To provide a more comprehensive approach to public health, dietary indices have been developed to assess dietary quality, dietary inflammation and risk factors for non-communicable diseases. Thus far, their use in the context of placental development is limited and associations with offspring outcomes have been inconsistent. Although epidemiological studies have focused on the role of maternal diet on foetal programming, the underlying mechanisms are still poorly understood. Some evidence suggests these associations may be driven by placental and epigenetic changes. In this narrative review, we examine the current literature regarding relationships between key validated diet quality scores (Dietary Inflammatory Index [DII], Mediterranean diet [MD], Healthy Eating Index [HEI], Alternative Healthy Eating Index [AHEI], Dietary Approaches to Stop Hypertension [DASH], Glycaemic Index [GI] and Glycaemic Load [GL]) in pregnancy and birth and long-term offspring outcomes. We summarise findings, discuss potential underlying placental and epigenetic mechanisms, in particular DNA methylation, and highlight the need for further research and public health strategies that incorporate diet quality and epigenetics.

Overweight and obesity in pregnancy: their impact on epigenetics

Over the last few decades, the prevalence of obesity has risen to epidemic proportions worldwide. Consequently, the number of obesity in pregnancy has risen drastically. Gestational overweight and obesity are associated with impaired outcomes for mother and child. Furthermore, studies show that maternal obesity can lead to long-term consequences in the offspring, increasing the risk for obesity and cardiometabolic disease in later life. In addition to genetic mechanisms, mounting evidence demonstrates the induction of epigenetic alterations by maternal obesity, which can affect the offspring’s phenotype, thereby influencing the later risk of obesity and cardiometabolic disease. Clear evidence in this regard comes from various animal models of maternal obesity. Evidence derived from clinical studies remains limited. The current article gives an overview of pathophysiological changes associated with maternal obesity and their consequences on placental structure and function. Furthermore, a short excurse is given on epigenetic mechanisms and emerging data regarding a putative interaction between metabolism and epigenetics. Finally, a summary of important findings of animal and clinical studies investigating maternal obesity-related epigenetic effects is presented also addressing current limitations of clinical studies.

Stromal Cell-Derived Factor (SDF) 2 and the Endoplasmic Reticulum Stress Response of Trophoblast Cells in Gestational Diabetes Mellitus and In vitro Hyperglycaemic Condition

BACKGROUND AND AIM

The endoplasmic reticulum (ER) stress response and the unfolded protein response (UPR) are essential cellular mechanisms to ensure the proper functioning of ER in adverse conditions. However, activation of these pathways has also been associated with insulin resistance and cell death in pathological conditions such as diabetes mellitus. In the present study, we investigated whether stromal cell-derived factor 2 (SDF2)-an ER stress-responsive factor-is related to ER response in placental cells exposed to maternal gestational diabetes mellitus (GDM) or to a hyperglycaemic in vitro condition.

OBJECTIVE

The study aimed to investigate the role of SDF2 in BeWo cells , a trophoblast cell line originating from choriocarcinoma , and in placental tissue under hyperglycaemic conditions.

METHODS

Protein levels of SDF2 and UPR factors, glucose-related protein 78 (GRP78) and eukaryotic initiation factor 2 alpha (elF2 alpha) were evaluated in the placentae of pregnant women diagnosed with GDM and treated by diet-control (insulin was added when necessary). The mRNA expression of SDF2 and UPR factors CHOP and sXBP1 were assessed in cultured BeWo cells challenged with glucose and treated with or without insulin.

RESULTS

SDF2 expression was increased in the placentae of GDM women treated with diet. However, its values were similar to those of normoglycemic controls when the GDM women were treated with insulin and diet. BeWo cells cultured with high glucose and insulin showed decreased SDF2 expression, while high glucose increased CHOP and sXBP1 expression, which was then significantly reverted with insulin treatment.

CONCLUSION

Our findings extend the understanding of ER stress and SDF2 expression in placentae exposed to hyperglycaemia, highlighting the relevance of insulin in reducing the levels of ER stress factors in placental cells. Understanding the effect of ER stress partners such as SDF2 on signalling pathways involved in gestation, complicated by hyperglycaemia, is pivotal for basic biomedical research and may lead to new therapeutic possibilities.

Fetal and Placental Weight in Pre-Gestational Maternal Obesity (PGMO) vs. Excessive Gestational Weight Gain (EGWG)-A Preliminary Approach to the Perinatal Outcomes in Diet-Controlled Gestational Diabetes Mellitus

Both pre-gestational maternal obesity (PGMO) and excessive gestational weight gain (EGWG) increase the risk of gestational diabetes mellitus (GDM). Here, we conducted a retrospective study to comparatively examine the relation between fetal birth weight (FW) and placental weight (PW) in PGMO (n = 100) compared to EGWG (n = 100) with respect to perinatal outcomes in diet-controlled GDM. The control group was made up of 100 healthy pregnancies. The mean FW and the mean PW in EGWG were correlated with lowered fetal weight/placental weight ratio (FW/PW ratio). The percentage of births completed by cesarean section accounted for 47%, 32%, and 18% of all deliveries (EGWG, PGMO, and controls, respectively), with the predominance of FW-related indications for cesarean section. Extended postpartum hospital stays due to neonate were more frequent in EGWG, especially due to neonatal jaundice (p < 0.05). The results indicate the higher perinatal risk in mothers with EGWG compared to PGMO during GDM-complicated pregnancy. Further in-depth comparative studies involving larger patient pools are needed to validate these findings, the intent of which is to formulate guidelines for GDM patients in respect to management of PGMO and EGWG.

[Comparative morphofunctional analysis of the state of fetoplacental complex in diabetes mellitus (literature review)]

This article reviews the literature on placental morphofunctional changes in placenta of patients with type 1 and type 2 diabetes mellitus and gestational diabetes mellitus. The detailed analysis of features of pathogenesis of various abnormalities of the fetoplacental complex depending on the type of diabetes, its influence on the formation of the placental vascular bed. The analysis of mechanisms of development of placenta formation disorders, pathologies of placental vascular bed, the role of hyperglycemia and hyperinsulinemia in villous maturation, placental weight gain, perinatal outcomes. The discussed anomalies have a significant impact on the fetoplacental complex, acting as epigenetic factors, forming the environment for the fetus, which may later affect the health of the unborn child. They lead to adverse perinatal outcomes, including high infant morbidity and mortality. Literature search was performed in Russian (eLibrary, CyberLeninka.ru) and international (PubMed, Cochrane Library) databases in Russian and English languages. The free access to the full text of the articles was in priority. The selection of sources was prioritized for the period from 2016 to 2020. However, due to the lack of knowledge of the chosen topic, the selection of sources was dated from 2001.

Mitochondrial dysfunction in the fetoplacental unit in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a disease of pregnancy that is associated with d-glucose intolerance and foeto-placental vascular dysfunction. GMD causes mitochondrial dysfunction in the placental endothelium and trophoblast. Additionally, GDM is associated with reduced placental oxidative phosphorylation due to diminished activity of the mitochondrial F₀F₁-ATP synthase (complex V). This phenomenon may result from a higher generation of reactive superoxide anion and nitric oxide. Placental mitochondrial biogenesis and mitophagy work in concert to maintain cell homeostasis and are vital mechanisms securing the efficient generation of ATP, whose demand is higher in pregnancy, ensuring foetal growth and development. Additional factors disturbing placental ATP synthase activity in GDM include pre-gestational maternal obesity or overweight, intracellular pH, miRNAs, fatty acid oxidation, and foetal (and 'placental') sex. GDM is also associated with maternal and foetal hyperinsulinaemia, altered circulating levels of adiponectin and leptin, and the accumulation of extracellular adenosine. Here, we reviewed the potential interplay between these molecules or metabolic conditions on the mechanisms of mitochondrial dysfunction in the foeto-placental unit in GDM pregnancies.