Metformin use in pregnancy: promises and uncertainties

Metformin in pregnancy and childhood neurodevelopmental outcomes: a systematic review and meta-analysis

OBJECTIVE

This study aimed to examine the impact of maternal metformin use during pregnancy on offspring neurodevelopmental outcomes.

DATA SOURCES

MEDLINE, Embase, and Web of Science (Core Collection) were searched from inception until July 1, 2023.

STUDY ELIGIBILITY CRITERIA

Studies of women who received treatment with metformin at any stage of pregnancy for any indication with neurodevelopmental data available for their offspring were included. Studies without a control group were excluded. Randomized controlled trials, case-control, cohort, and cross-sectional studies were included in the review.

METHODS

Studies were screened for inclusion and data were extracted independently by 2 reviewers. Risk of bias was assessed using a modified version of the Newcastle-Ottawa Scale for nonrandomized studies, and the Risk of Bias 2 tool for randomized trials.

RESULTS

A total of 7 studies met the inclusion criteria, including a combined cohort of 14,042 children with 7641 children who were exposed and followed for up to 14 years of age. Metformin use during pregnancy was not associated with neurodevelopmental delay in infancy (relative risk, 1.09; 95% confidence interval, 0.54-2.17; 3 studies; 9668 children) or at ages 3 to 5 years (relative risk, 0.90; 95% confidence interval, 0.56-1.45; 2 studies; 6118 children). When compared with unexposed peers, metformin use during pregnancy was not associated with altered motor scores (mean difference, 0.30; 95% confidence interval, -1.15 to 1.74; 3 studies; 714 children) or cognitive scores (mean difference, -0.45; 95% confidence interval, -1.45 to 0.55; 4 studies; 734 children). Studies that were included were of high quality and deemed to be at low risk of bias.

CONCLUSION

In utero exposure to metformin does not seem to be associated with adverse neurodevelopmental outcomes in children up to the age of 14 years. These findings provide reassurance to clinicians and pregnant women considering metformin use during pregnancy.

Longitudinal integrative cell-free DNA analysis in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) presents varied manifestations throughout pregnancy and poses a complex clinical challenge. High-depth cell-free DNA (cfDNA) sequencing analysis holds promise in advancing our understanding of GDM pathogenesis and prediction. In 299 women with GDM and 299 matched healthy pregnant women, distinct cfDNA fragment characteristics associated with GDM are identified throughout pregnancy. Integrating cfDNA profiles with lipidomic and single-cell transcriptomic data elucidates functional changes linked to altered lipid metabolism processes in GDM. Transcription start site (TSS) scores in 50 feature genes are used as the cfDNA signature to distinguish GDM cases from controls effectively. Notably, differential coverage of the islet acinar marker gene PRSS1 emerges as a valuable biomarker for GDM. A specialized neural network model is developed, predicting GDM occurrence and validated across two independent cohorts. This research underscores the high-depth cfDNA early prediction and characterization of GDM, offering insights into its molecular underpinnings and potential clinical applications.

Metformin beyond type 2 diabetes: Emerging and potential new indications

Metformin is best known as a foundational therapy for type 2 diabetes but is also used in other contexts in clinical medicine with a number of emerging and potential indications. Many of its beneficial effects may be mediated by modest effects on weight loss and insulin sensitivity, but it has multiple other known mechanisms of action. Current clinical uses beyond type 2 diabetes include: polycystic ovarian syndrome; diabetes in pregnancy/gestational diabetes; prevention of type 2 diabetes in prediabetes; and adjunct therapy in type 1 diabetes. As metformin has been in clinical use for almost 70 years, much of the underpinning evidence for its use in these conditions is, by definition, based on trials conducted before the advent of contemporary evidence-based medicine. As a result, some of the above-established uses are 'off-label' in many regulatory territories and their use varies accordingly in different countries. Going forward, several current 'repurposing' investigational uses of metformin are also being investigated: prevention of cancer (including in Li Fraumeni syndrome), renal protection, Alzheimer's disease, metabolic dysfunction-associated steatotic liver disease and promotion of healthy ageing. Despite the longevity of metformin and its important current roles beyond type 2 diabetes in clinical medicine, it has further potential and much research is ongoing.

Metformin use in pregnancy: What about long-term effects in offspring?

Metformin use in pregnancy is increasing worldwide. Unlike insulin, metformin crosses the placenta. Consequently, maternal and fetal concentrations are comparable. Teratogenic effects are not reported, nor are adverse pregnancy outcomes. Reduced risk of hypertensive disorders, hypoglycemia, and macrosomia are potential benefits, together with lower gestational weight gain. Although metformin has been prescribed for pregnant women during the last 40 years, long-term data regarding offspring outcomes are still lacking. Independent of maternal glycemic control, recent meta-analyses report lower birthweight but accelerated postnatal growth and higher body mass index in metformin-exposed children. The longest follow-up study of placebo-controlled metformin exposure in utero found an increased prevalence of central adiposity and obesity among children 5-10 years old. Recently, a Danish study reported a threefold increased risk of genital anomalies in boys, whose fathers used metformin around the time of conception. This commentary addresses the current controversies on metformin use in pregnancy.

Absence of Metformin in Fetal Circulation Following Maternal Administration in Late Gestation Pregnant Sheep

In human pregnancy, metformin administered to the mother crosses the placenta resulting in metformin exposure to the fetus. However, the effects of metformin exposure on the fetus are poorly understood and difficult to study in humans. Pregnant sheep are a powerful large animal model for studying fetal physiology. The objective of this study was to determine if maternally administered metformin at human dose-equivalent concentrations crosses the ovine placenta and equilibrates in the fetal circulation. To test this, metformin was administered to the pregnant ewe via continuous intravenous infusion or supplementation in the drinking water. Both administration routes increased maternal metformin concentrations to human dose-equivalent concentrations of ~ 10 µM, yet metformin was negligible in the fetus even after 3-4 days of maternal administration. In cotyledon and caruncle tissue, expression levels of the major metformin uptake transporter organic cation transporter 1 (OCT1) were < 1% of expression levels in the fetal liver, a tissue with abundant expression. Expression of other putative uptake transporters OCT2 and OCT3, and efflux transporters multidrug and toxin extrusion (MATE)1 and MATE2were more abundant. These results demonstrate that the ovine placenta is impermeable to maternal metformin administration. This is likely due to anatomical differences and increased interhaemal distance between the maternal and umbilical circulations in the ovine versus human placenta limiting placental metformin transport.

Relationships Between Exposure to Gestational Diabetes Treatment and Neonatal Anthropometry: Evidence from the Born in Bradford (BiB) Cohort

OBJECTIVES

To examine the relationships between gestational diabetes mellitus (GDM) treatment and neonatal anthropometry.

METHODS

Covariate-adjusted multivariable linear regression analyses were used in 9907 offspring of the Born in Bradford cohort. GDM treatment type (lifestyle changes advice only, lifestyle changes and insulin or lifestyle changes and metformin) was the exposure, offspring born to mothers without GDM the control, and birth weight, head, mid-arm and abdominal circumference, and subscapular and triceps skinfold thickness the outcomes.

RESULTS

Lower birth weight in offspring exposed to insulin (- 117.2 g (95% CI - 173.8, - 60.7)) and metformin (- 200.3 g (- 328.5, - 72.1)) compared to offspring not exposed to GDM was partly attributed to lower gestational age at birth and greater proportion of Pakistani mothers in the treatment groups. Higher subscapular skinfolds in offspring exposed to treatment compared to those not exposed to GDM was partly attributed to higher maternal glucose concentrations at diagnosis. In fully adjusted analyses, offspring exposed to GDM treatment had lower weight, smaller abdominal circumference and skinfolds at birth than those not exposed to GDM. Metformin exposure was associated with smaller offspring mid-arm circumference (- 0.3 cm (- 0.6, - 0.07)) than insulin exposure in fully adjusted models with no other differences found.

CONCLUSIONS FOR PRACTICE

Offspring exposed to GDM treatment were lighter and smaller at birth than those not exposed to GDM. Metformin-exposed offspring had largely comparable birth anthropometric characteristics to those exposed to insulin.

Fetal and post-natal outcomes in offspring after intrauterine metformin exposure: A systematic review and meta-analysis of animal experiments

AIMS

The impact of maternal metformin use during pregnancy on fetal, infant, childhood and adolescent growth, development, and health remains unclear. Our objective was to systematically review the available evidence from animal experiments on the effects of intrauterine metformin exposure on offspring's anthropometric, cardiovascular and metabolic outcomes.

METHODS

A systematic search was conducted in PUBMED and EMBASE from inception (searched on 12th April 2023). We extracted original, controlled animal studies that investigated the effects of maternal metformin use during pregnancy on offspring anthropometric, cardiovascular and metabolic measurements. Subsequently, risk of bias was assessed and meta-analyses using the standardized mean difference and a random effects model were conducted for all outcomes containing data from 3 or more studies. Subgroup analyses were planned for species, strain, sex and type of model in the case of 10 comparisons or more per subgroup.

RESULTS

We included 37 articles (n = 3133 offspring from n = 716 litters, containing n = 51 comparisons) in this review, mostly (95%) on rodent models and 5% pig models. Follow-up of offspring ranged from birth to 2 years of age. Thirty four of the included articles could be included in the meta-analysis. No significant effects in the overall meta-analysis of metformin on any of the anthropometric, cardiovascular and metabolic offspring outcome measures were identified. Between-studies heterogeneity was high, and risk of bias was unclear in most studies as a consequence of poor reporting of essential methodological details.

CONCLUSION

This systematic review was unable to establish effects of metformin treatment during pregnancy on anthropometric, cardiovascular and metabolic outcomes in non-human offspring. Heterogeneity between studies was high and reporting of methodological details often limited. This highlights a need for additional high-quality research both in humans and model systems to allow firm conclusions to be established. Future research should include focus on the effects of metformin in older offspring age groups, and on outcomes which have gone uninvestigated to date.

Position paper of the Italian Association of Medical Diabetologists (AMD), Italian Society of Diabetology (SID), and the Italian Study Group of Diabetes in pregnancy: Metformin use in pregnancy

OBJECTIVE

This document purpose is to create an evidence-based position statement on the role of metformin therapy in pregnancy complicated by obesity, gestational diabetes (GDM), type 2 diabetes mellitus (T2DM), polycystic ovary syndrome (PCOS) and in women undergoing assisted reproductive technology (ART).

METHODS

A comprehensive review of international diabetes guidelines and a search of medical literature was performed to identify studies presenting data on the use of metformin in pregnancy. The document was approved by the councils of the two scientific societies.

RESULTS

In condition affecting the fertility, as PCOS, metformin use in pre-conception or early in pregnancy may be beneficial for clinical pregnancy, even in ART treatment, and in obese-PCOS women may reduce preterm delivery. In obese women, even in the presence of GDM or T2DM, metformin use in pregnancy is associated with a lower gestational weight gain. In pregnancy complicated by diabetes (GDM or T2DM), metformin improves maternal glycemic control and may reduce insulin dose. Neonatal and infant outcomes related to metformin exposure in utero are lacking. Metformin use in women with GDM or T2DM is associated with lower birth weight. However, an increased tendency to overweight-obesity has been observed in children, later in life.

CONCLUSIONS

Metformin may represent a therapeutic option in selected women with obesity, PCOS, GDM, T2DM, and in women undergoing ART. However, more research is required specifically on the long-term effects of in utero exposition to metformin.

Insulin requiring Gestational Diabetes: Risk factors and correlation with postpartum diabetes and prediabetes

Objective

A2 gestational diabetes mellitus (A2GDM) is a more severe form of GDM that requires additional medical intervention, such as insulin or oral antidiabetic drug (OAD). The present study explored the determinants of A2GDM and analyzed the associated risk of post-partum diabetes or prediabetes.

Methods

This retrospective study included 247 pregnant women, diagnosed with GDM and followed up until delivery at the Obstetric Medicine Clinic of King Abdulaziz University Hospital, Jeddah, Saudi Arabia, between January 2014 and January 2018. Women with personal history of diabetes or prediabetes were excluded. Collected data included patient's age, body mass index, personal history of thyroid dysfunction and GDM, HbA1c level at diagnosis, management of GDM (diet only, insulin, or OAD), and postpartum metabolic assessment.

Results

The prevalence of A2GDM was 29.6%, of which 21.5% were insulin-requiring and 8.1% were OAD-requiring cases. The risk of A2GDM was independently associated with a positive history of GDM (OR=3.19, 95% CI = 1.41-7.20) and HbA1c >7% (OR=8.66, 95%CI = 2.15- 34.94); the model explained 20% of the variance of A2GDM. The postpartum assessment showed that 10.1% have developed prediabetes, while no one developed overt diabetes. Postpartum prediabetes was independently predicted by age category ≥45 years (OR=39.94, 95%CI = 4.62-345.06), history of GDM (OR=0.18, 95%CI = 0.03 - 0.97), and A2GDM (OR=6.96, 95%CI = 1.91-25.42).

Conclusion

Approximately one-third of GDM patients in our institution require insulin or OAD for glycemic control and are at high risk of developing prediabetes postpartum. Adherence to and effectiveness of medical nutrition therapy should be further explored among GDM patients to improve their glycemic control and both maternal and fetal prognosis.

Metformin Disrupts Signaling and Metabolism in Fetal Hepatocytes

Metformin is used by women during pregnancy to manage diabetes and crosses the placenta, yet its effects on the fetus are unclear. We show that the liver is a site of metformin action in fetal sheep and macaques, given relatively abundant OCT1 transporter expression and hepatic uptake following metformin infusion into fetal sheep. To determine the effects of metformin action, we performed studies in primary hepatocytes from fetal sheep, fetal macaques, and juvenile macaques. Metformin increases AMP-activated protein kinase (AMPK) signaling, decreases mammalian target of rapamycin (mTOR) signaling, and decreases glucose production in fetal and juvenile hepatocytes. Metformin also decreases oxygen consumption in fetal hepatocytes. Unique to fetal hepatocytes, metformin activates stress pathways (e.g., increased PGC1A gene expression, NRF-2 protein abundance, and phosphorylation of eIF2α and CREB proteins) alongside perturbations in hepatokine expression (e.g., increased growth/differentiation factor 15 [GDF15] and fibroblast growth factor 21 [FGF21] expression and decreased insulin-like growth factor 2 [IGF2] expression). Similarly, in liver tissue from sheep fetuses infused with metformin in vivo, AMPK phosphorylation, NRF-2 protein, and PGC1A expression are increased. These results demonstrate disruption of signaling and metabolism, induction of stress, and alterations in hepatokine expression in association with metformin exposure in fetal hepatocytes.

ARTICLE HIGHLIGHTS

The major metformin uptake transporter OCT1 is expressed in the fetal liver, and fetal hepatic uptake of metformin is observed in vivo. Metformin activates AMPK, reduces glucose production, and decreases oxygen consumption in fetal hepatocytes, demonstrating similar effects as in juvenile hepatocytes. Unique to fetal hepatocytes, metformin activates metabolic stress pathways and alters the expression of secreted growth factors and hepatokines. Disruption of signaling and metabolism with increased stress pathways and reduced anabolic pathways by metformin in the fetal liver may underlie reduced growth in fetuses exposed to metformin.

Immunomodulatory Effects of Metformin Treatment in Pregnant Women With PCOS

CONTEXT

Polycystic ovary syndrome (PCOS) is a common endocrine disorder associated with low-grade systemic inflammation and increased risk of pregnancy complications. Metformin treatment reduces the risk of late miscarriage and preterm birth in pregnant women with PCOS. Whether the protective effect of metformin involves immunological changes has not been determined.

OBJECTIVE

To investigate the effect of metformin on the maternal immunological status in women with PCOS.

METHODS

A post-hoc analysis was performed of two randomized controlled trials, PregMet and PregMet2, including longitudinal maternal serum samples from 615 women with PCOS. Women were randomized to metformin or placebo from first trimester to delivery. Twenty-two cytokines and C-reactive protein were measured in serum sampled at gestational weeks 5 to 12, 19, 32, and 36.

RESULTS

Metformin treatment was associated with higher serum levels of several multifunctional cytokines throughout pregnancy, with the strongest effect on eotaxin (P < .001), interleukin-17 (P = .03), and basic fibroblast growth factor (P = .04). Assessment of the combined cytokine development confirmed the impact of metformin on half of the 22 cytokines. The immunomodulating effect of metformin was more potent in normal weight and overweight women than in obese women. Moreover, normoandrogenic women had the strongest effect of metformin in early pregnancy, whereas hyperandrogenic women presented increasing effect throughout pregnancy.

CONCLUSION

It appears that metformin has immunomodulating rather than anti-inflammatory properties in pregnancy. Its effect on the serum levels of many multifunctional cytokines demonstrates robust, persisting, and body mass-dependent immune mobilization in pregnant women with PCOS.

Metformin Impacts Human Syncytiotrophoblast Mitochondrial Function from Pregnancies Complicated by Obesity and Gestational Diabetes Mellitus in a Sexually Dimorphic Manner

Maternal obesity and gestational diabetes mellitus (GDM) are associated with placental dysfunction, small for gestational age (SGA) offspring, and programming of adult-onset disease. We examine how metformin, commonly used to treat type A2 GDM, affects placental metabolism as well as mitochondrial content and function. Syncytiotrophoblasts (STBs) were prepared from placentas of male and female fetuses collected at term cesarean section from lean (pre-pregnancy BMI < 25), obese (BMI > 30), and obese A2GDM women. Metformin treatment (0.001-10 mM) of STB caused no change in non-mitochondrial respiration but significant concentration-dependent (1 and 10 mM) decreases in basal, maximal, and ATP-linked respiration and spare capacity. Respiration linked to proton leak was significantly increased in STB of male A2GDM placentas at low metformin concentrations. Metformin concentrations ≥1 mM increased glycolysis in STB from placentas from lean women, but only improved glycolytic capacity in female STB. Whereas metformin had little effect on superoxide generation from male STB of any group, it gave a concentration-dependent decrease in superoxide generation from female STB of lean and obese women. Fewer mitochondria were observed in STB from obese women and male STB from lean women with increasing metformin concentration. Metformin affects STB mitochondrial function in a sexually dimorphic manner but at concentrations above those reported in maternal circulation (approximately 0.01 mM) in women treated with metformin for GDM.

Polycystic Ovary Syndrome: Challenges and Possible Solutions

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders in women of reproductive age. This syndrome not only impairs female fertility but also increases the risk of obesity, diabetes, dyslipidemia, cardiovascular diseases, psychological diseases, and other health problems. Additionality, because of the high clinical heterogeneity, the current pathogenesis of PCOS is still unclear. There is still a large gap in precise diagnosis and individualized treatment. We summarize the present findings concerning the genetics, epigenetics, gut microbiota, corticolimbic brain responses, and metabolomics of the PCOS pathogenesis mechanism, highlight the remaining challenges in PCOS phenotyping and potential treatment approaches, and explain the vicious circle of intergenerational transmission of PCOS, which might provide more thoughts for better PCOS management in the future.

[Clinical practice recommendations for diabetes in pregnancy (Update 2023)]

In 1989 the St. Vincent Declaration aimed to achieve comparable pregnancy outcomes in women with diabetes and those with normal glucose tolerance. However, currently women with pre-gestational diabetes still feature a higher risk of perinatal morbidity and even increased mortality. This fact is mostly ascribed to a persistently low rate of pregnancy planning and pre-pregnancy care with optimization of metabolic control prior to conception. All women should be experienced in the management of their therapy and on stable glycemic control prior to conception. In addition, thyroid dysfunction, hypertension as well as the presence of diabetic complications should be excluded or treated adequately before pregnancy in order to decrease the risk for a progression of complications during pregnancy as well as maternal and fetal morbidity. Near normoglycaemia and HbA1c in the normal range are targets for treatment, preferably without the induction of frequent resp. severe hypoglycaemic reactions. Especially in women with type 1 diabetes mellitus the risk of hypoglycemia is high in early pregnancy, but it decreases with the progression of pregnancy due to hormonal changes causing an increase of insulin resistance. In addition, obesity increases worldwide and contributes to higher numbers of women at childbearing age with type 2 diabetes mellitus and adverse pregnancy outcomes. Intensified insulin therapy with multiple daily insulin injections and pump treatment are equally effective in reaching good metabolic control during pregnancy. Insulin is the primary treatment option. Continuous glucose monitoring often adds to achieve targets. Oral glucose lowering drugs (Metformin) may be considered in obese women with type 2 diabetes mellitus to increase insulin sensitivity but need to be prescribed cautiously due to crossing the placenta and lack of long-time follow up data of the offspring (shared decision making). Due to increased risk for preeclampsia in women with diabetes screening needs to be performed. Regular obstetric care as well as an interdisciplinary treatment approach are necessary to improve metabolic control and ensure the healthy development of the offspring.

Efficacy and safety of metformin compared to insulin in gestational diabetes: a systemic review and meta-analysis of Chinese randomized controlled trials

BACKGROUND

Metformin is widely used for the treatment of gestational diabetes. Although some meta-analyses are conducted on the efficacy and safety of metformin, none of them are focused on the Chinese population. The efficacy and safety of metformin in the Chinese GDM population are unknown.

AIM

The study aimed to compare metformin to insulin regarding the safety and efficacy in Chinese GDM patients using randomized controlled trials (RCTs) conducted in China.

METHOD

Chinese databases (Wanfang, CNKI, VIP, and CBM), PubMed, Embase, Cochrane library, and Scopus were searched for RCTs. The last search date was October 18, 2021.

RESULTS

Fifty RCTs (4663 patients) were included in this study after screening. Six outcomes were analyzed. In the main analysis, metformin had lower risk of respiratory distress syndrome (RDS, OR, 0.28; 95% CI 0.16-0.51; P < 0.0001), premature birth (OR, 0.42; 95% CI 0.21-0.85, P = 0.02), and neonatal hypoglycemia (OR, 0.34; 95% CI 0.24-0.48; P < 0.00001) compared to insulin. Moreover, the metformin group is better than the insulin group concerning all other outcomes such as maternal glycemic control and glycated hemoglobin. Subgroup analysis confirmed that metformin has better outcomes than all types of insulin except for RDS, premature birth, 2 h postprandial blood glucose, and glycated hemoglobin.

CONCLUSION

Metformin is considered to be a safe and effective alternative to insulin for the management of GDM if patients refuse insulin due to any reasons in China.

A Clinical Update on Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) traditionally refers to abnormal glucose tolerance with onset or first recognition during pregnancy. GDM has long been associated with obstetric and neonatal complications primarily relating to higher infant birthweight and is increasingly recognized as a risk factor for future maternal and offspring cardiometabolic disease. The prevalence of GDM continues to rise internationally due to epidemiological factors including the increase in background rates of obesity in women of reproductive age and rising maternal age and the implementation of the revised International Association of the Diabetes and Pregnancy Study Groups' criteria and diagnostic procedures for GDM. The current lack of international consensus for the diagnosis of GDM reflects its complex historical evolution and pragmatic antenatal resource considerations given GDM is now 1 of the most common complications of pregnancy. Regardless, the contemporary clinical approach to GDM should be informed not only by its short-term complications but also by its longer term prognosis. Recent data demonstrate the effect of early in utero exposure to maternal hyperglycemia, with evidence for fetal overgrowth present prior to the traditional diagnosis of GDM from 24 weeks' gestation, as well as the durable adverse impact of maternal hyperglycemia on child and adolescent metabolism. The major contribution of GDM to the global epidemic of intergenerational cardiometabolic disease highlights the importance of identifying GDM as an early risk factor for type 2 diabetes and cardiovascular disease, broadening the prevailing clinical approach to address longer term maternal and offspring complications following a diagnosis of GDM.

Maternal Treatment with Metformin Persistently Ameliorates High-Fat Diet-Induced Metabolic Symptoms and Modulates Gut Microbiota in Rat Offspring

A maternal high-fat (HF) diet has long-term deleterious effect on offspring. This study aims to evaluate whether maternal metformin (MT) treatment ameliorates the adverse effects of maternal HF diet on offspring and the role of gut microbiota in it. Pregnant Sprague-Dawley rats were randomly assigned to a HF diet (60% fat) or a standard chow diet (11.8% fat) group, and part of the HF diet group rats were co-treated with MT via drinking water (300 mg/kg/day), resulting in three groups according to maternal diet and MT treatment during gestation and lactation. All offspring were weaned on a chow diet. A maternal HF diet showed a significant deleterious effect on offspring’s metabolic phenotype and induced colonic inflammation and gut-barrier disruption through the reshaped gut microbiota. The daily oral administration of MT to HF-fed dams during gestation and lactation reversed the dysbiosis of gut microbiota in both dams and adult offspring. The hypothalamic TGR5 expression and plasma bile acids composition in adult male offspring was restored by maternal MT treatment, which could regulate hypothalamic appetite-related peptides expression and alleviate inflammation, thereby improving male offspring’s metabolic phenotype. The present study indicates that targeting the gut–brain axis through the mother may be an effective strategy to control the metabolic phenotype of offspring.

Maternal but not fetoplacental health can be improved by metformin in a murine diet-induced model of maternal obesity and glucose intolerance

Maternal obesity is a global problem that increases the risk of short- and long-term adverse outcomes for mother and child, many of which are linked to gestational diabetes mellitus. Effective treatments are essential to prevent the transmission of poor metabolic health from mother to child. Metformin is an effective glucose lowering drug commonly used to treat gestational diabetes mellitus; however, its wider effects on maternal and fetal health are poorly explored. In this study we used a mouse (C57Bl6/J) model of diet-induced (high sugar/high fat) maternal obesity to explore the impact of metformin on maternal and feto-placental health. Metformin (300 mg kg-1  day-1 ) was given to obese females via the diet and was shown to achieve clinically relevant concentrations in maternal serum (1669 ± 568 nM in late pregnancy). Obese dams developed glucose intolerance during pregnancy and had reduced uterine artery compliance. Metformin treatment of obese dams improved maternal glucose tolerance, reduced maternal fat mass and restored uterine artery function. Placental efficiency was reduced in obese dams, with increased calcification and reduced labyrinthine area. Consequently, fetuses from obese dams weighed less (P < 0.001) at the end of gestation. Despite normalisation of maternal parameters, metformin did not correct placental structure or fetal growth restriction. Metformin levels were substantial in the placenta and fetal circulation (109.7 ± 125.4 nmol g-1 in the placenta and 2063 ± 2327 nM in fetal plasma). These findings reveal the distinct effects of metformin administration during pregnancy on mother and fetus and highlight the complex balance of risk vs. benefits that are weighed in obstetric medical treatments. KEY POINTS: Maternal obesity and gestational diabetes mellitus have detrimental short- and long-term effects for mother and child. Metformin is commonly used to treat gestational diabetes mellitus in many populations worldwide but the effects on fetus and placenta are unknown. In a mouse model of diet-induced obesity and glucose intolerance in pregnancy we show reduced uterine artery compliance, placental structural changes and reduced fetal growth. Metformin treatment improved maternal metabolic health and uterine artery compliance but did not rescue obesity-induced changes in the fetus or placenta. Metformin crossed the placenta into the fetal circulation and entered fetal tissue. Metformin has beneficial effects on maternal health beyond glycaemic control. However, despite improvements in maternal physiology, metformin did not prevent fetal growth restriction or placental ageing. The high uptake of metformin into the placental and fetal circulation highlights the potential for direct immediate effects of metformin on the fetus with possible long-term consequences postnatally.

Effect of ginger in the treatment of nausea and vomiting compared with vitamin B6 and placebo during pregnancy: a meta-analysis

INTRODUCTION

Nausea and vomiting (NV) affect up to 85% of pregnant women, which has multiple effects on pregnancy outcome. The truth etiology of nausea and vomiting in pregnancy (NVP) is still unknown. Considering the potential teratogenic effect in fetus due to chemical drugs, ginger can be used to treat nausea and vomiting during pregnancy. Reports have shown that ginger can reduce the severity of NV, however, these results are controversial. Therefore, this meta-analysis aims to explore the effect of ginger in the treatment of nausea and vomiting during pregnancy compared with placebo and vitamin B6.

METHODS

The randomized control trials (RCTs) on the association with ginger and pregnancy-related nausea and vomiting were searched and identified in two databases Web of Science and PubMed (up to April 2019). Stata software was used to conduct meta-analysis. In addition, the source of heterogeneity explored by metaregression, sensitivity analysis, subgroup analyses, the publication bias were assessed by Egger's tests and Funnel plot, p < .05 was considered to be significant.

RESULTS

Thirteen studies involving 1174 subjects were included in this meta-analysis. The result demonstrated that ginger intervention has significant effect in improving general symptom of NVP [OR = 7.475, 95% CI = (4.133, 13.520), I2 = 30.1%], relieving severity of nausea [SMD = 0.821, 95% CI = (0.585, 1.056), I2 = 38.9%], but not significant in reducing vomiting [SMD = 0.549, 95% CI = (-0.268, 1.365), I2 = 91.4%], compared with placebo. Besides, ginger intervention has no significant effect on improving general symptom of NVP [OR = 1.239, 95% CI = (0.495, 3.102), I2 = 57.3%], relieving severity of nausea [SMD = 0.199, 95% CI = (-0.102, 0.500), I2 = 65.7%], reducing vomiting [SMD = 0.331, 95% CI = (-0.145, 0.808), I2 = 85.9%], compared with vitamin B6.

CONCLUSIONS

Ginger supplementation significantly relieve general NVP symptom and nausea compared with placebo, but no significant effect on vomiting. Moreover, ginger is more effective than vitamin B6 in treating NVP, although, there were no significant differences. Further, rigidly designed RCTs with larger sample sizes are needed to verify the effectiveness of ginger supplementation for treatment NVP compared with vitamin B6.

The Use of Oral Hypoglycemic Agents during Pregnancy: An Alternative to Insulin?

OBJECTIVE

Gestational Diabetes Mellitus (GDM) and Type 2 Diabetes Mellitus (DM2) are metabolic disorders characterized by increased insulin resistance. Although insulin is the treatment of choice in pregnant patients with DM, the prescription of oral hypoglycemic agents (OHA) has been increasing among practitioners. This study aimed to evaluate the maternal and neonatal outcomes when oral hypoglycemic agents were used in diabetic pregnant women.

METHODS

Medical records from the Maternal-Infant Care Unit Clinics SoM-UPR (n=149) were reviewed. Patients that were treated with metformin, sulfonylurea or insulin were included. Maternal and neonatal outcomes were compared between groups.

RESULTS

Patient's mean age was 28 ± 6 years. The majority had GDM (91%). The most common comorbidity was hypertension (9.9%). Lifestyle modification was used as treatment in 77% of patients during the second trimester, but its use decreased to 33% during the third trimester. Insulin was the treatment of choice. Among the OHA, sulfonylurea was preferred. Postprandial glucose levels were lower in patients who used insulin as compared to those without medications.

CONCLUSION

No significant differences were found in maternal outcomes such as C-section, induction of labor, episiotomy or preterm labor, or neonatal outcomes such as macrosomia, neonatal hypoglycemia or congenital abnormalities among treatment groups. OHA can be considered as an alternative to insulin for the treatment of DM during pregnancy in selected cases.

Associations between maternal characteristics and pharmaceutical treatment of gestational diabetes: an analysis of the UK Born in Bradford (BiB) cohort study

OBJECTIVES

To identify the maternal characteristics associated with pharmaceutical treatment of gestational diabetes mellitus (GDM).

DESIGN

Prospective birth cohort study.

SETTING

Bradford, UK.

PARTICIPANTS

762 women from the Born in Bradford (BiB) cohort who were treated for GDM in a singleton pregnancy. BiB cohort participants were recruited from 2007 to 2010. All women booked for delivery were screened for GDM between 26 and 28 weeks of gestation using a 75 g 2-hour oral glucose tolerance test (OGTT).

OUTCOME MEASURE

GDM treatment type: lifestyle changes advice (lifestyle changes), lifestyle changes advice with supplementary insulin (insulin) and lifestyle changes advice with supplementary metformin (metformin).

RESULTS

244 (32%) women were prescribed lifestyle changes advice alone while 518 (68%) were offered supplemental pharmaceutical treatment. The odds of receiving pharmaceutical treatment relative to lifestyle changes advice alone were increased for mothers who were obese (OR 4.6, 95% CI 2.8 to 7.5), those who smoked (OR 2.6, 95% CI 1.2 to 5.5) and had higher fasting glucose levels at OGTT (OR 2.1, 95% CI 1.6 to 2.7). The odds of being prescribed pharmaceutical treatment rather than lifestyle changes advice were lower for Pakistani women (OR 0.7, 95% CI 0.4 to 1.0)) than White British women. Relative to insulin treatment, metformin was more likely to be offered to obese women than normal weight women (relative risk ratio, RRR 3.2, 95% CI 1.3 to 7.8) and less likely to be prescribed to women with higher fasting glucose concentrations at OGTT (RRR 0.3, 95% CI 0.2 to 0.6).

CONCLUSIONS

In the BiB cohort, GDM pharmaceutical treatment tended to be prescribed to women who were obese, White British, who smoked and had more severe hyperglycaemia. The characteristics of metformin-treated mothers differed from those of insulin-treated mothers as they were more likely to be obese but had lower glucose concentrations at diagnosis.

Neonatal metformin short exposure inhibits male reproductive dysfunction caused by a high-fat diet in adult rats

Metformin (Met) is widely used to control blood glucose levels and acts on various organs, including reproductive tissues, to improve reproductive and lifespan. This study evaluated whether neonatal Met exposure prevented male reproductive dysfunction caused by being overweight during adulthood. Randomized Wistar rat pups received an intraperitoneal injection from postnatal days (PNDs) 1 to 12of saline (Sal; 0.9% NaCl/day in 2mL/kg) or Met (100 mg/kg/day in 2 mL/kg). From PNDs 60 to 90, the animals received a regular (R; 4.5% fat; Sal R and Met R groups) or a high-fat (HF; 35% fat; Sal HF and Met HF groups) diet. At PND 90, all animals were euthanized to evaluate their biometric and reproductive parameters. The Sal and Met groups with R showed similar body weights, however, the HF diet increased the body weight in both groups. The Sal HF group showed testicular damage regarding in antioxidant status and inflammatory profile in the epididymal cauda. The HF diet reduced Leydig and Sertoli cells numbers, with lower sperm quality. The Met R animals showed positive reproductive programming, due to improved antioxidant defense, inflammatory biomarkers, and sperm morphology. Met HF prevented HF diet damage to reproductive organs and sperm morphology, but not to sperm motility. Early Met exposure positively affected the male reproductive system of adult rats, preventing reproductive HF disorders. STATEMENT OF NOVELTY AND SIGNIFICANCE: Metformin is used to control type 2 diabetes mellitus and can act to improve metabolism and lifespan. Metformin avoidance is recommended during pregnancy, but there is no information regarding its use when breastfeeding. For the first time, we showed in this current study that metformin positively acts in the male reproductive tissues and helps involved in later life. These data showed a better antioxidant defense and anti-inflammatory profile of Metformin animals than Saline animals and might directly improve reproductive organs morphophysiology and sperm morphology. Also, the neonatal Met application programs the male reproduction to counterbalance damages from an obesogenic environment in later life.

Current Therapeutic Use of Metformin During Pregnancy: Maternal Changes, Postnatal Effects and Safety

Metformin is one of the most easily available medications for diabetes and has a relatively low cost. It is not only used in diabetes but is also effective in polycystic ovarian syndrome (PCOS) and obesity. Although insulin is the first choice when it comes to treating pregnant women with gestational diabetes mellitus (GDM), metformin has also been debated as a good choice after modification of diet. As metformin passes through the placenta, it is essential to know its consequence of leading to insulin resistance in the fetus as well as the impact on postnatal development. The use of metformin during GDM has raised many trials demonstrating that outcomes from the use of metformin are similar to those achieved with insulin. Follow-up studies were also conducted that assessed the impact on children exposed to metformin in utero. This review highlights the experimental evidence relating to the use of metformin during pregnancy for different conditions, and its impact on the growth and development of offspring.

Metformin ameliorates maternal high-fat diet-induced maternal dysbiosis and fetal liver apoptosis

BACKGROUND

The deleterious effect of maternal high-fat diet (HFD) on the fetal rat liver may cause later development of non-alcoholic fatty liver disease (NAFLD). The aim of this study was to evaluate the effect of maternal HFD-induced maternal hepatic steatosis and dysbiosis on the fetal liver and intestines, and the effect of prenatal metformin in a rat model.

METHODS

Sprague-Dawley rats were assigned to three groups (N = 6 in each group). Before mating, the rats were randomly assigned to HFD or normal-chow diet (NCD) group for 7 weeks. After mating, the HFD group rats were continued with high-fat diet during pregnancy and some of the HFD group rats were co-treated with metformin (HFMf) via drinking water during pregnancy. All maternal rats and their fetuses were sacrificed on gestational day 21. The liver and intestinal tissues of both maternal and fetal rats were analyzed. In addition, microbial deoxyribonucleic acid extracted from the maternal fecal samples was analyzed.

RESULTS

HFD resulted in maternal weight gain during pregnancy, intrahepatic lipid accumulation, and change in the serum short-chain fatty acid profile, intestinal tight junctions, and dysbiosis in maternal rats. The effect of HFD on maternal rats was alleviated by prenatal metformin, which also ameliorated inflammation and apoptosis in the fetal liver and intestines.

CONCLUSIONS

This study demonstrated the beneficial effects of prenatal metformin on maternal liver steatosis, focusing on the gut-liver axis. In addition, the present study indicates that prenatal metformin could ameliorate maternal HFD-induced inflammation and apoptosis in the fetal liver and intestines. This beneficial effect of in-utero exposure of metformin on fetal liver and intestines has not been reported. This study supports the use of prenatal metformin for pregnant obese women.

Metformin Perturbs Pancreatic Differentiation From Human Embryonic Stem Cells

Metformin is becoming a popular treatment before and during pregnancy, but current literature on in utero exposure to metformin lacks long-term clinical trials and mechanistic studies. Current literature on the effects of metformin on mature pancreatic β-cells highlights its dual, opposing, protective, or inhibitory effects, depending on metabolic environment. However, the impact of metformin on developing human pancreatic β-cells remains unknown. In this study, we investigated the potential effects of metformin exposure on human pancreatic β-cell development and function in vitro. In the absence of metabolic challenges such as high levels of glucose and fatty acids, metformin exposure impaired the development and function of pancreatic β-cells, with downregulation of pancreatic genes and dysfunctional mitochondrial respiration. It also affected the insulin secretion function of pancreatic β-cells. These findings call for further in-depth evaluation of the exposure of human embryonic and fetal tissue during pregnancy to metformin and its implications for long-term offspring health.

Biguanides drugs: Past success stories and promising future for drug discovery

Biguanides have attracted much attention a century ago and showed resurgent interest in recent years after a long period of dormancy. They constitute an important class of therapeutic agents suitable for the treatment of a wide spectrum of diseases. Therapeutic indications of biguanides include antidiabetic, antimalarial, antiviral, antiplaque, and bactericidal applications. This review presents an extensive overview of the biological activity of biguanides and different mechanisms of action of currently marketed biguanide-containing drugs, as well as their pharmacological properties when applicable. We highlight the recent developments in research on biguanide compounds, with a primary focus on studies on metformin in the field of oncology. We aim to provide a critical overview of all main bioactive biguanide compounds and discuss future perspectives for the design of new drugs based on the biguanide fragment.

Hyperglycemia in pregnancy: sleep alterations, comorbidities and pharmacotherapy

OBJECTIVE

To investigate sleep alterations and associated factors in pregnant diabetic women (n=141).

METHODS

Sleep profile, sociodemographics and clinical information were collected. Poor sleep quality (Pittsburgh Sleep Quality Index >5) and excessive daytime sleepiness (Epworth Sleepiness Scale ≥10), sleep duration (h), sleep latency (min), frequent sleep interruption and short sleep (≤6 h) were assessed in type 1 diabetes mellitus (16.3%), type 2 diabetes mellitus (25.5%) and gestational diabetes mellitus (58.2%).

RESULTS

Poor sleep quality was found in 58.8% of patients and daytime sleepiness in 25.7%, regardless of hyperglycemia etiology. No correlation existed between daytime sleepiness and poor sleep quality (Pearson correlation r=0.02, p=0.84). Short sleep duration occurred in 1/3 of patients (31.2%). Sleep interruptions due to frequent urination affected 72% of all and sleep interruptions due to any cause 71.2%. Metformin was used by 65.7% of type 2 diabetes mellitus and 28.7% of gestational diabetes mellitus. In gestational diabetes mellitus, parity number was independently associated with poor sleep quality (p=0.02; OR=1.90; 95%CI 1.07-3.36) and metformin use was also independently associated with poor sleep quality (p=0.03; OR=2.36; 95%CI 1.05-5.29).

CONCLUSIONS

Our study originally shows that poor sleep quality and excessive daytime sleepiness are frequent in diabetic pregnancy due to different etiologies. Interestingly, only in gestational diabetes mellitus, metformin therapy and higher parity were associated with poor sleep quality.

Interaction between Metformin, Folate and Vitamin B12 and the Potential Impact on Fetal Growth and Long-Term Metabolic Health in Diabetic Pregnancies

Metformin is the first-line treatment for many people with type 2 diabetes mellitus (T2DM) and gestational diabetes mellitus (GDM) to maintain glycaemic control. Recent evidence suggests metformin can cross the placenta during pregnancy, thereby exposing the fetus to high concentrations of metformin and potentially restricting placental and fetal growth. Offspring exposed to metformin during gestation are at increased risk of being born small for gestational age (SGA) and show signs of ‘catch up’ growth and obesity during childhood which increases their risk of future cardiometabolic diseases. The mechanisms by which metformin impacts on the fetal growth and long-term health of the offspring remain to be established. Metformin is associated with maternal vitamin B₁₂ deficiency and antifolate like activity. Vitamin B₁₂ and folate balance is vital for one carbon metabolism, which is essential for DNA methylation and purine/pyrimidine synthesis of nucleic acids. Folate:vitamin B₁₂ imbalance induced by metformin may lead to genomic instability and aberrant gene expression, thus promoting fetal programming. Mitochondrial aerobic respiration may also be affected, thereby inhibiting placental and fetal growth, and suppressing mammalian target of rapamycin (mTOR) activity for cellular nutrient transport. Vitamin supplementation, before or during metformin treatment in pregnancy, could be a promising strategy to improve maternal vitamin B₁₂ and folate levels and reduce the incidence of SGA births and childhood obesity. Heterogeneous diagnostic and screening criteria for GDM and the transient nature of nutrient biomarkers have led to inconsistencies in clinical study designs to investigate the effects of metformin on folate:vitamin B₁₂ balance and child development. As rates of diabetes in pregnancy continue to escalate, more women are likely to be prescribed metformin; thus, it is of paramount importance to improve our understanding of metformin’s transgenerational effects to develop prophylactic strategies for the prevention of adverse fetal outcomes.

Long-Term Metabolic Consequences in Patients with a History of Gestational Diabetes

Gestational diabetes mellitus is a common metabolic complication of pregnancy. Universal guidelines on gestational diabetes have been impeded by the long-term controversies on its definition and screening strategies. The prevalence of gestational diabetes is rising all over the world, is significantly influenced by ethnicity and its rise is mainly attributed to increasing maternal obesity and age. Gestational diabetes mellitus has important long-term implications, including gestational diabetes recurrence, increased risk for developing type 2 diabetes, metabolic syndrome and cardiovascular disease for the mother. Gestational diabetes mellitus may be viewed as a chronic metabolic disorder that is identified in women during gestation and may provide a unique opportunity for the early identification and primary prevention of type 2 diabetes mellitus and cardiovascular disease in these women. In this mini-review, the evolution of screening tests for gestational diabetes and guidelines are briefly described and metabolic and cardiovascular long-term consequences of women with a history of gestational diabetes are summarized. A summary of our own St. Mary's Hospital-UK Research series on long-term metabolic consequences of 368 women with a history of gestational diabetes of 3 different ethnic groups and 482 control women is also included. We found that approximately 2 years following delivery, 37% of women with a history of gestational diabetes had abnormal glucose concentrations, but, most importantly, even those who were normoglycaemic, postpartum displayed metabolic abnormalities on detailed testing. Future research needs to focus on the prevention of gestational diabetes long-term complications, but also in identification of pre-pregnancy predictors and risk reduction before conception.

Management of Women with Polycystic Ovary Syndrome During Pregnancy

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy among reproductive age women and is associated with subfertility and adverse perinatal outcomes, which may include early pregnancy loss, gestational diabetes mellitus, hypertensive spectrum disorder, preterm birth, fetal growth disorders, and cesarean deliveries. The phenotypic heterogeneity, different diagnostic criteria, and PCOS-related conditions that women enter pregnancy with have limited evidenced-based studies and guidelines to reduce pregnancy complications among this high-risk population. This review summarizes the available evidence on the approach and management of women with PCOS preconception, prenatal, and postpartum.

The Current and Potential Therapeutic Use of Metformin-The Good Old Drug

Metformin, one of the oldest oral antidiabetic agents and still recommended by almost all current guidelines as the first-line treatment for type 2 diabetes mellitus (T2DM), has become the medication with steadily increasing potential therapeutic indications. A broad spectrum of experimental and clinical studies showed that metformin has a pleiotropic activity and favorable effect in different pathological conditions, including prediabetes, type 1 diabetes mellitus (T1DM) and gestational diabetes mellitus (GDM). Moreover, there are numerous studies, meta-analyses and population studies indicating that metformin is safe and well tolerated and may be associated with cardioprotective and nephroprotective effect. Recently, it has also been reported in some studies, but not all, that metformin, besides improvement of glucose homeostasis, may possibly reduce the risk of cancer development, inhibit the incidence of neurodegenerative disease and prolong the lifespan. This paper presents some arguments supporting the initiation of metformin in patients with newly diagnosed T2DM, especially those without cardiovascular risk factors or without established cardiovascular disease or advanced kidney insufficiency at the time of new guidelines favoring new drugs with pleotropic effects complimentary to glucose control. Moreover, it focuses on the potential beneficial effects of metformin in patients with T2DM and coexisting chronic diseases.

Metabolic phenotypes of early gestational diabetes mellitus and their association with adverse pregnancy outcomes

AIMS

To describe the metabolic phenotypes of early gestational diabetes mellitus and their association with adverse pregnancy outcomes.

METHODS

We performed a post hoc analysis using data from the Vitamin D And Lifestyle Intervention for gestational diabetes prevention (DALI) trial conducted across nine European countries (2012-2014). In women with a BMI ≥29 kg/m² , insulin resistance and secretion were estimated from the oral glucose tolerance test values performed before 20 weeks, using homeostatic model assessment of insulin resistance and Stumvoll first-phase indices, respectively. Women with early gestational diabetes, defined by the International Association of Diabetes and Pregnancy Study Groups criteria, were classified into three groups: GDM-R (above-median insulin resistance alone), GDM-S (below-median insulin secretion alone), and GDM-B (combination of both) and the few remaining women were excluded.

RESULTS

Compared with women in the normal glucose tolerance group (n = 651), women in the GDM-R group (n = 143) had higher fasting and post-load glucose values and insulin levels, with a greater risk of having large-for-gestational age babies [adjusted odds ratio 3.30 (95% CI 1.50-7.50)] and caesarean section [adjusted odds ratio 2.30 (95% CI 1.20-4.40)]. Women in the GDM-S (n = 37) and GDM-B (n = 56) groups had comparable pregnancy outcomes with those in the normal glucose tolerance group.

CONCLUSIONS

In overweight and obese women with early gestational diabetes, higher degree of insulin resistance alone was more likely to be associated with adverse pregnancy outcomes than lower insulin secretion alone or a combination of both.

Placental mitochondrial dysfunction with metabolic diseases: Therapeutic approaches

Both obesity and gestational diabetes mellitus (GDM) lead to poor maternal and fetal outcomes, including pregnancy complications, fetal growth issues, stillbirth, and developmental programming of adult-onset disease in the offspring. Increased placental oxidative/nitrative stress and reduced placental (trophoblast) mitochondrial respiration occur in association with the altered maternal metabolic milieu of obesity and GDM. The effect is particularly evident when the fetus is male, suggesting a sexually dimorphic influence on the placenta. In addition, obesity and GDM are associated with inflexibility in trophoblast, limiting the ability to switch between usage of glucose, fatty acids, and glutamine as substrates for oxidative phosphorylation, again in a sexually dimorphic manner. Here we review mechanisms underlying placental mitochondrial dysfunction: its relationship to maternal and fetal outcomes and the influence of fetal sex. Prevention of placental oxidative stress and mitochondrial dysfunction may improve pregnancy outcomes. We outline pathways to ameliorate deficient mitochondrial respiration, particularly the benefits and pitfalls of mitochondria-targeted antioxidants.

O-GlcNAcylation in Hyperglycemic Pregnancies: Impact on Placental Function

The dynamic cycling of N-acetylglucosamine, termed as O-GlcNAcylation, is a post-translational modification of proteins and is involved in the regulation of fundamental cellular processes. It is controlled by two essential enzymes, O-GlcNAc transferase and O-GlcNAcase. O-GlcNAcylation serves as a modulator in placental tissue; furthermore, increased levels of protein O-GlcNAcylation have been observed in women with hyperglycemia during pregnancy, which may affect the short-and long-term development of offspring. In this review, we focus on the impact of O-GlcNAcylation on placental functions in hyperglycemia-associated pregnancies. We discuss the following topics: effect of O-GlcNAcylation on placental development and its association with hyperglycemia; maternal-fetal nutrition transport, particularly glucose transport, via the mammalian target of rapamycin and AMP-activated protein kinase pathways; and the two-sided regulatory effect of O-GlcNAcylation on inflammation. As O-GlcNAcylation in the placental tissues of pregnant women with hyperglycemia influences near- and long-term development of offspring, research in this field has significant therapeutic relevance.

Developmental effects of in utero metformin exposure

According to the Developmental Origins of Health and Disease (DOHaD) hypothesis, the intrauterine environment influences fetal programming and development, affecting offspring disease susceptibility in adulthood. In recent years, therapeutic use of the Type 2 diabetes drug metformin has expanded to the treatment of pre-diabetes, polycystic ovarian syndrome, and gestational diabetes. Because metformin both undergoes renal excretion and binds to receptors on the placenta, the fetus receives equivalent maternal dosing. Although no teratogenic nor short-term harmful fetal impact of metformin is known to occur, the effects of metformin exposure on longer-range offspring development have not yet been fully elucidated. This review encapsulates the (albeit limited) existing knowledge regarding the potential longer-term impact of intrauterine metformin exposure on the development of key organs including the liver, central nervous system, heart, gut, and endocrine pancreas in animal models and humans. We discuss molecular and cellular mechanisms that would be altered in response to treatment and describe the potential consequences of these developmental changes on postnatal health. Further studies regarding the influence of metformin exposure on fetal programming and adult metabolic health will provide necessary insight to its long-term risks, benefits, and limitations in order to guide decisions for use of metformin during pregnancy.

Current Researches, Rationale, Plausibility, and Evidence Gaps on Metformin for the Management of Hypertensive Disorders of Pregnancy

Hypertensive disorders of pregnancy (HDP) are a group of morbid pregnancy complications, with preeclampsia (PE) being the most common subclassification among them. PE affects 2%–8% of pregnancies globally and threatens maternal and fetal health seriously. However, the only effective treatment of PE to date is the timely termination of pregnancy, albeit with increased perinatal risks. Hence, more emerging therapies for PE management are in urgent need. Originally introduced as the first-line therapy for type 2 diabetes mellitus, metformin (MET) has now been found in clinical trials to significantly reduce the incidence of gestational hypertension and PE in pregnant women with PE-related risks, including but not limited to pregestational diabetes mellitus, gestational diabetes mellitus, polycystic ovary syndrome, or obesity. Additionally, existing clinical data have preliminarily ensured the safety of taking MET during human pregnancies. Relevant lab studies have indicated that the underlying mechanism includes angiogenesis promotion, endothelial protection, anti-inflammatory effects, and particularly protective effects on trophoblast cells against the risk factors, which are beneficial to placental development. Together with its global availability, easy administration, and low cost, MET is expected to be a promising option for the prevention and treatment of PE. Nevertheless, there are still some limitations in current studies, and the design of the relevant research scheme is supposed to be further improved in the future. Herein, we summarize the relevant clinical and experimental researches to discuss the rationale, safety, and feasibility of MET for the management of HDP. At the end of the article, gaps in current researches are proposed. Concretely, experimental MET concentration and PE models should be chosen cautiously. Besides, the clinical trial protocol should be further optimized to evaluate the reduction in the prevalence of PE as a primary endpoint. All of those evidence gaps may be of guiding significance to improve the design of relevant experiments and clinical trials in the future.

Gestational Diabetes Mellitus-Innovative Approach to Prediction, Diagnosis, Management, and Prevention of Future NCD-Mother and Offspring

Gestational diabetes mellitus (GDM) is the commonest medical complication of pregnancy. The association of GDM with immediate pregnancy complications including excess fetal growth and adiposity with subsequent risk of birth trauma and with hypertensive disorders of pregnancy is well recognized. However, the associations with wide ranges of longer-term health outcomes for mother and baby, including the lifetime risks of obesity, pre-diabetes, and diabetes and cardiovascular disease have received less attention and few health systems address these important issues in a systematic way. This article reviews historical and recent data regarding prediction of GDM using demographic, clinical, and biochemical parameters. We evaluate current and potential future diagnostic approaches designed to most effectively identify GDM and extend this analysis into a critical evaluation of lifestyle and nutritional/pharmacologic interventions designed to prevent the development of GDM. The general approach to management of GDM during pregnancy is then discussed and the major final focus of the article revolves around the importance of a GDM diagnosis as a future marker of the risk of non-communicable disease (NCD), in particular pre-diabetes, diabetes, and cardiovascular disease, both in mother and offspring.

The Effects of Maternal Metformin Treatment on Late Prenatal and Early Postnatal Development of the Offspring Are Modulated by Sex

Metformin is currently used to improve pregnancy outcome in women affected by polycystic ovary syndrome (PCOS) or diabetes. However, metformin may also be useful in pregnancies at risk of intrauterine growth restriction (IUGR) since it improves placental efficiency and the fetuses' developmental competence. There is no data on the duration of the effect of this treatment from the prenatal up to the postnatal stages. Therefore, the present trial aimed at determining the impact of metformin treatment on the offspring neonatal traits and early postnatal development (i.e., during lactation) using an in vivo swine model. The results support that maternal metformin treatment during pregnancy induces protective changes in body shape and composition of the progeny (i.e., larger head size and body length at birth and higher total viscera weight at weaning). However, there were also major effects of the offspring sex (smaller corpulence in females and lower relative weight of main viscerae in males), which should be considered for further preclinical studies and when even the current clinical application in women affected by PCOS or diabetes is implemented.

Early metformin treatment improves pancreatic function and prevents metabolic dysfunction in early overfeeding male rats at adulthood

NEW FINDINGS

What is the central question of this study? Studies reported the efficacy of metformin as a promising drug for preventing or treating of metabolic diseases. Nutrient stresses during neonatal life increase long-term risk for cardiometabolic diseases. Can early metformin treatment prevent the malprogramming effects of early overfeeding? What is the main finding and its importance? Neonatal metformin treatment prevented early overfeeding-induced metabolic dysfunction in adult rats. Inhibition of early hyperinsulinaemia and adult hyperphagia might be associated with decreased metabolic disease risk in these animals. Therefore, interventions during infant development offer a key area for future research to identify potential strategies to prevent the long-term metabolic diseases. We suggest that metformin is a potential tool for intervention.

ABSTRACT

Given the need for studies investigating the possible long-term effects of metformin use at crucial stages of development, and taking into account the concept of metabolic programming, the present work aimed to evaluate whether early metformin treatment might program rats to resist the development of adult metabolic dysfunctions caused by overnutrition during the neonatal suckling phase. Wistar rats raised in small litters (SLs, three pups per dam) and normal litters (NLs, nine pups per dam) were used as models of early overfeeding and normal feeding, respectively. During the first 12 days of suckling, animals from SL and NL groups received metformin, whereas the controls received saline injections. Food intake and body weight were monitored from weaning until 90 days of age, when biometric and biochemical parameters were assessed. The metformin treatment decreased insulin concentrations in pups from SL groups, and as adults, these animals showed improvements in glucose tolerance, insulin sensitivity, body weight gain, white fat pad stores and food intake. Low-glucose insulinotrophic effects were observed in pancreatic islets from both NL and SL groups. These results indicate that early postnatal treatment with metformin inhibits early overfeeding-induced metabolic dysfunctions in adult rats.

Association of pregnancy outcomes in women with type 2 diabetes treated with metformin versus insulin when becoming pregnant

BACKGROUND

Metformin use in pregnancy is controversial because metformin crosses the placenta and the safety on the fetus has not been well-established. This retrospective study aimed to compare pregnancy outcomes in women with preexisting type 2 diabetes receiving metformin or standard insulin treatment.

METHODS

The cohort of this population-based study includes women of age 20-44 years with preexisting type 2 diabetes and singleton pregnancies in Taiwan between 2003 and 2014. Subjects were classified into three mutually exclusive groups according to glucose-lowering treatments received before and after becoming pregnant: insulin group, switching group (metformin to insulin), and metformin group. A generalized estimating equation model adjusted for patient age, duration of type 2 diabetes, hypertension, hyperlipidemia, retinopathy, and aspirin use was used to estimate the adjusted odds ratio (aOR) and 95% confidence interval (CI) of adverse pregnancy outcomes.

RESULTS

A total of 1166 pregnancies were identified in the insulin group (n = 222), the switching group (n = 318) and the metformin group (n = 626). The insulin group and the switching group had similar pregnancy outcomes for both the mother and fetus, including risk of primary cesarean section, pregnancy-related hypertension, preeclampsia, preterm birth (< 37 weeks), very preterm birth (< 32 weeks), low birth weight (< 2500 g), high birth weight (> 4000 g), large for gestational age, and congenital malformations. The metformin group had a lower risk of primary cesarean section (aOR = 0.57; 95% CI, 0.40-0.82) and congenital malformations (aOR, 0.51; 95% CI; 0.27-0.94) and similar risk for the other outcomes as compared with the insulin group.

CONCLUSIONS

Metformin therapy was not associated with increased adverse pregnancy outcomes in women with type 2 diabetes as compared with standard insulin therapy.

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.

Therapeutic doses of metformin do not have impact on angiogenesis in presence of sera from pre-eclamptic, IUGR and healthy pregnancies

Recent evidence suggests that metformin may prevent pre-eclampsia by reverting the angiogenic imbalance in maternal sera. In this study, we investigated effect of metformin on angiogenesis by quantifying tubule formation in a human-based in vitro test with co-culture of human adipose stromal cell (hASC) and human umbilical vein endothelial cell (HUVEC). A total of 20 pregnant women were recruited in the study. Serum samples were obtained from women with early- and late-onset pre-eclampsia and from women with pregnancies complicated by intrauterine growth restriction (IUGR) without pre-eclampsia (N = 5 in each of the three groups). Serum samples from women with healthy pregnancies served as controls (N = 5). The direct effect of metformin on angiogenesis was first assessed without maternal sera. Secondly, we investigated the impact of metformin on angiogenesis in the present of maternal sera. Metformin was used at 5, 50 and 600 µg/ml concentrations. Angiogenic and inflammatory biomarkers in maternal sera were analyzed by immunoassays. When the direct effect of metformin was studied, the two lowest concentrations of metformin did not affect tubule formation (angiogenesis), but the highest concentration inhibited angiogenesis. When metformin was supplemented at therapeutic concentrations of 5 and 50 µg/ml along with serum samples, there was no change in tubule formation in comparison to maternal sera alone. However, strong inhibitory effect on tubule formation was observed in all groups with the highest, non-therapeutic (600 µg/ml), concentration of metformin.

AMP-activated protein kinase activator AICAR attenuates hypoxia-induced murine fetal growth restriction in part by improving uterine artery blood flow

KEY POINTS

Pregnancy at high altitude is associated with a greater incidence of fetal growth restriction due, in part, to lesser uterine artery blood flow. AMP-activated protein kinase (AMPK) activation vasodilates arteries and may increase uterine artery blood flow. In this study, pharmacological activation of AMPK by the drug AICAR improved fetal growth and elevated uterine artery blood flow. These results suggest that AMPK activation is a potential strategy for improving fetal growth and raising uterine artery blood flow in pregnancy, which may be important in pregnancy disorders characterized by uteroplacental ischaemia and/or fetal hypoxia.

ABSTRACT

Uteroplacental hypoxia is associated with pregnancy disorders such as intrauterine growth restriction and preeclampsia, which are characterized by uteroplacental ischaemia and/or fetal hypoxia. Activation of AMP-activated protein kinase (AMPK) results in vasodilatation and is therefore a potential therapeutic strategy for restoring uteroplacental perfusion in pregnancy disorders. In this study, C57Bl/6 mice were treated with subcutaneous pellets containing vehicle, the AMPK activator AICAR (200 mg kg^-1 day^-1 ), or the AMPK inhibitor Compound C (20 mg kg^-1 day^-1 ) beginning on gestational day 13.5, and were exposed to hypoxia starting on gestational day 14.5 that induced intrauterine growth restriction. Pharmacological AMPK activation by AICAR partially prevented hypoxia-induced fetal growth restriction (P < 0.01), due in part to increased uterine artery blood flow (P < 0.0001). The proportion of total cardiac output flowing through the uterine artery was increased with AICAR in hypoxic mice (P < 0.001), suggesting that the vasodilator effect of AICAR was selective for the uterine circulation. Further, pharmacological inhibition of AMPK with Compound C reduced uterine artery diameter and increased uterine artery contractility in normoxic mice, providing evidence that physiological levels of AMPK activation are necessary for vasodilatation in healthy pregnancy. Two-way ANOVA analyses indicated that hypoxia reduced AMPK activation in the uterine artery and placenta, and AICAR increased AMPK activation in these tissues compared to vehicle. These findings provide support for further investigation into the utility of pharmacological AMPK activation for treatment of fetal growth restriction.

Metformin during Pregnancy: Effects on Offspring Development and Metabolic Function

Maternal obesity during pregnancy and gestational diabetes mellitus (GDM) are both associated with of several postnatal diseases in the offspring, including obesity, early onset hypertension, diabetes mellitus, and reproductive alterations. Metformin is an oral drug that is being evaluated to treat GDM, obesity-associated insulin resistance, and polycystic ovary syndrome (PCOS) during pregnancy. The beneficial effects of metformin on glycemia and pregnancy outcomes place it as a good alternative for its use during pregnancy. In this line of thought, improving the metabolic status of the pregnant mother by using metformin should avoid the consequences of insulin resistance on the offspring's fetal and postnatal development. However, some human and animal studies have shown that metformin during pregnancy could amplify these alterations and be associated with excessive postnatal weight gain and obesity. In this minireview, we discuss not only the clinical and experimental evidence that supports the benefits of using metformin during pregnancy but also the evidence showing a possible negative impact of this drug on the offspring's development.

Metformin in Pregnancy Study (MiPS): protocol for a systematic review with individual patient data meta-analysis

INTRODUCTION

Gestational diabetes mellitus (GDM) is a common disorder of pregnancy and contributes to adverse pregnancy outcomes. Metformin is often used for the prevention and management of GDM; however, its use in pregnancy continues to be debated. The Metformin in Pregnancy Study aims to use individual patient data (IPD) meta-analysis to clarify the efficacy and safety of metformin use in pregnancy and to identify relevant knowledge gaps.

METHODS AND ANALYSIS

MEDLINE, EMBASE and all Evidence-Based Medicine will be systematically searched for randomised controlled trials (RCT) testing the efficacy of metformin compared with placebo, usual care or other interventions in pregnant women. Two independent reviewers will assess eligibility using prespecified criteria and will conduct data extraction and quality appraisal of eligible studies. Authors of included trials will be contacted and asked to contribute IPD. Primary outcomes include maternal glycaemic parameters and GDM, as well as neonatal hypoglycaemia, anthropometry and gestational age at delivery. Other adverse maternal, birth and neonatal outcomes will be assessed as secondary outcomes. IPD from these RCTs will be harmonised and a two-step meta-analytic approach will be used to determine the efficacy and safety of metformin in pregnancy, with a priori adjustment for covariates and subgroups to examine effect moderators of treatment outcomes. Sensitivity analyses will assess heterogeneity, risk of bias and the impact of trials which have not provided IPD.

ETHICS AND DISSEMINATION

All IPD will be deidentified and studies contributing IPD will have ethical approval from their respective local ethics committees. This study will provide robust evidence regarding the efficacy and safety of metformin use in pregnancy, and may identify subgroups of patients who may benefit most from this treatment modality. Findings will be published in peer-reviewed journals and disseminated at scientific meetings, providing much needed evidence to inform clinical and public health actions in this area.