Metformin reduces maternal weight gain in obese pregnant women: A systematic review and meta-analysis of two randomized controlled trials

Metformin impairs trophoblast metabolism and differentiation in a dose-dependent manner

Metformin is a widely prescribed medication whose mechanism of action is not completely defined and whose role in gestational diabetes management remains controversial. In addition to increasing the risk of fetal growth abnormalities and preeclampsia, gestational diabetes is associated with abnormalities in placental development including impairments in trophoblast differentiation. Given that metformin impacts cellular differentiation events in other systems, we assessed metformin's impact on trophoblast metabolism and differentiation. Using established cell culture models of trophoblast differentiation, oxygen consumption rates and relative metabolite abundance were determined following 200 µM (therapeutic range) and 2000 µM (supra-therapeutic range) metformin treatment using Seahorse and mass-spectrometry approaches. While no differences in oxygen consumption rates or relative metabolite abundance were detected between vehicle and 200 µM metformin-treated cells, 2000 µM metformin impaired oxidative metabolism and increased the abundance of lactate and TCA cycle intermediates, α-ketoglutarate, succinate, and malate. Examining differentiation, treatment with 2000 μM, but not 200 µM metformin, impaired HCG production and expression of multiple trophoblast differentiation markers. Overall, this work suggests that supra-therapeutic concentrations of metformin impair trophoblast metabolism and differentiation whereas metformin concentrations in the therapeutic range do not strongly impact these processes.

A Women's health perspective on managing obesity

While the prevalence of obesity in US men and women is nearly equivalent, obesity management in women requires a different approach that considers age and life stage in development including sexual maturation/reproduction, menopause and post-menopause. In this review, the diagnosis and treatment of obesity using lifestyle modification, pharmacotherapy and metabolic and bariatric surgery are discussed from a women's health perspective, with emphasis on management during pregnancy and post-partum.

The role of ultrasonographic adipose tissue thickness measurement in the first trimester in predicting gestational diabetes: a prospective study

BACKGROUND

This prospective observational study aimed to assess the association between maternal abdominal subcutaneous and visceral fat thickness measured with ultrasound scan during the first trimester and the risk of developing gestational diabetes mellitus (GDM).

METHODS

We recruited 43 non-diabetic women with singleton pregnancy between 11 and 14 week of gestation and evaluated ultrasonographic measurements of subcutaneous fat thickness (SFT) and preperitoneal fat (PF) above the umbilicus. During the 2^nd trimester, GDM screening was performed by 75 g two-hour oral glucose tolerance test (OGTT) and diagnosis was made when one or more plasma glucose values meets or exceeds the values indicated by International Association of the Diabetes and Pregnancy Study Groups (IADPSG).

RESULTS

Among the 43 woman, 8 developed GDM (18.6%). Of these 37,5% (N.=3) had been diagnosed with GDM during a previous pregnancy, with a statistically significant correlation (P=0.035). Mean SFT for all patients was significantly higher in the GDM group compared to non-GDM group (27.30±8.78 mm vs. 18.56±9.99 mm; P=0.049). Mean PF for all women showed a statistically significant correlation with GDM (13.27±9.07 mm for non GDM group vs. 23.52±10.24 mm for GDM group; P=0.038).

CONCLUSIONS

Abdominal adiposity, both subcutaneous and visceral, seem to be a suitable predictor of GDM in early pregnancy and it can be easily assessed during a first trimester routine ultrasound, although further studies are needed to evaluate their role in the screening protocols.

Predictors for pharmacological therapy and perinatal outcomes with metformin treatment in women with gestational diabetes

BACKGROUND

The prevalence of gestational diabetes mellitus (GDM) has been increasing in Australia and worldwide. The study aims were to examine, in comparison with dietary intervention, perinatal outcomes for women with gestational diabetes who were attending a single hospital clinic and to identify predictors for their pharmacological GDM treatment.

METHODS

A prospective, observational study of women with GDM, treated with "Diet, N= 50", "Metformin, N = 35", "Metformin and Insulin, N = 46" or "Insulin, N = 20".

FINDINGS

The mean BMI for the whole cohort was 25.8 ± 4.7 kg/m². The Metformin group, compared to the Diet group, had OR=3.1 (95% CI:1.13 to 8.25) for caesarean section birth (LSCS) compared to normal vaginal birth mode with no longer such a significant association after controlling for the number of their elective LSCS. The insulin treated group had the highest number of small for gestational age neonates (20%, p<0.05) with neonatal hypoglycaemia (25%, p< 0.05). Fasting glucose value on oral GTT (glucose tolerance test) was the strongest predictor for a pharmacological intervention requirement with OR = 2.77 (95CI%: 1.16 to 6.61), followed by timing of OGTT with OR=0.90 (95% CI: 0.83 to 0.97) and previous pregnancy loss with OR=0.28 (95% CI:0.10 to 0.74).

INTERPRETATION

These data suggest that metformin may be a safe alternative treatment to insulin treatment in GDM. Raised fasting glucose on oral GTT was the strongest indicator that GDM women with BMI < 35 kg/m² may require pharmacological therapy. Further studies are needed to identify the most effective and safe management of gestational diabetes within the public hospital setting.

AUSTRALIAN NEW ZEALAND CLINICAL TRIAL REGISTRY ANZCTR TRIAL ID

ACTRN12620000397910.

A Review on the Use of Metformin in Pregnancy and Its Associated Fetal Outcomes

A commonly used first-line anti-diabetic medication, metformin, has been used in pregnancy. The drug is known to have specific effects on different organs around the body. One of these organs includes the ovaries. Therefore, for more than 40 years, it has often been prescribed for maternal obesity along with gestational diabetes mellitus. Untreated pregnancies like these frequently result in complications for both the mother and the fetus, like macrosomia, pregnancy-induced hypertension, obstructed labor, stillbirths, and perinatal deaths. In addition, there is also evidence that these mothers tend to develop type II diabetes mellitus during their pregnancy and even a few years post-delivery. These complications can be controlled or even reduced with the help of metformin, sometimes combining it with insulin or clomiphene citrate if required. There is still a need to cautiously prescribe the drug by outweighing its benefits against the risk associated with it. The current research on the subject leans more towards the benefits offered to the mother during pregnancy. Only a few randomized, controlled trials have been conducted on the fetal condition after the mother has been administered metformin.

Furthermore, these studies lack the appropriate sample size and long-term follow-up on these metformin-exposed offspring. As a result, there are no reliable data available to clinicians and physicians about the drug. Owing to its benefits in certain pregnancies, it is less likely that the drug will cease to be prescribed. Therefore, it becomes increasingly imperative to conduct more research on this topic to ensure the drug is safe for the mother and the offspring.

Prevalence of Gestational Diabetes in preCOVID-19 and COVID-19 Years and Its Impact on Pregnancy: A 5-Year Retrospective Study

Gestational diabetes mellitus (GDM) affects a total of 3% to 9% of all pregnancies. It has a high impact on both mother and baby, increases the perinatal risks, and predicts the presence of long-term chronic metabolic complications. The aim of our study is to determine the incidence of GDM in tertiary hospitals in the west part of Romania to lay out the risk factors associated with GDM and to observe the evolution of pregnancy among patients with this pathology by emphasizing the state of birth of the fetus, the birth weight, and the way of birth. We also want to compare the prevalence of GDM in preCOVID-19 (Coronavirus disease) versus COVID-19 years. The study took place between January 2017 and December 2021 at the Municipal Emergency Hospital of Timisoara, Romania. The proportion of births with GDM was significantly increased during the COVID-19 period compared to the preCOVID-19 period (chi2 Fisher exact test, p < 0.001). The period 2020−2021 represents a significant risk factor for GDM births (OR = 1.87, with 95% CI = [1.30, 2.67]). COVID years represent a risk period for developing gestational diabetes, which can be explained by reduced physical activity, anxiety, or modified dietary habits, even if the follow-up period was not impacted.

Progesterone Attenuates SIRT1-Deficiency-Mediated Pre-Eclampsia

Pre-eclampsia is a severe hypertensive disorder of pregnancy (HDP), mainly characterized by new-onset hypertension with proteinuria after 20-week gestation. Sirtuin1 (SIRT1), a class III histone deacetylase, is associated with the regulation of various pathophysiological processes, including inflammation, immune response, metabolism, and autophagy. However, the effect of SIRT1 in the pathogenesis of pre-eclampsia remains to be elucidated. In this study, we found that the expression of SIRT1 was relatively lower in the placentas and serum samples of pre-eclampsia patients. Typical pre-eclampsia-like symptoms, such as hypertension, proteinuria, fetal growth restriction, kidney injury, and a narrow placental labyrinth layer, were observed in SIRT1 knockdown (SIRT1^+/−) mice. Of note, these performances could be improved after the intraperitoneal injection of SIRT1 agonist SRT2104. More importantly, we found that the efficacy of progesterone on attenuating symptoms of PE was profoundly better than that of metformin in SIRT1^+/− mice. In addition, our results suggested that progesterone can promote the invasion and inhibit the apoptosis of trophoblasts. These data suggest that SIRT1 plays an important role in pre-eclampsia and that progesterone alleviates pre-eclampsia-like symptoms mediated by SIRT1 deficiency.

Physical Exercise vs. Metformin to Improve Delivery- and Newborn-Related Outcomes Among Pregnant Women With Overweight: A Network Meta-Analysis

Background: Overweight/obesity is associated with the risk of delivery- and newborn-related complications in pregnancy. Interventions such as exercise or metformin could reduce the risk of these complications. Objective: To estimate and compare the effects of different types of exercise interventions (i.e., aerobic, resistance, combined exercise) and metformin on delivery- and newborn-related outcomes among pregnant women with overweight/obesity. Methods: MEDLINE, Scopus, Web of Science, Cochrane Library databases and the gray literature were searched from inception to September 2021. This systematic review was registered in PROSPERO (CDR: 42019121715). Randomized controlled trials (RCTs) of metformin or an exercise intervention aimed at preventing cesarean section, preterm birth, macrosomia, or birth weight among pregnant women with overweight/obesity were included. Random effects meta-analyses and frequentist network meta-analyses (NMA) were conducted for each outcome. Results: Fifteen RCTs were included. In the NMA, metformin reduced the risk of cesarean section (RR = 0.66, 95% CI: 0.46, 0.95), combined exercise reduced the risk of macrosomia (RR = 0.37, 95% CI: 0.14, 0.95), and aerobic exercise reduced birth weight (mean difference = -96.66 g, 95% CI: -192.45, -0.88). In the subgroup among pregnant women with obesity, metformin reduced the risk of cesarean section (RR = 0.66, 95% CI: 0.45, 0.97). Conclusions: Combined exercise could reduce the risk of macrosomia in pregnant women with overweight, whereas metformin could reduce the risk of cesarean section in pregnant women with obesity. However, previous evidence suggests a larger effect of physical exercise in other outcomes for this population group. Therefore, the medicalization of healthy pregnant women with obesity is not justified by the current evidence. Systematic Review Registration: PROSPERO: CRD42019121715; https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42019121715.

Exercise versus Metformin to Improve Pregnancy Outcomes among Overweight Pregnant Women: A Systematic Review and Network Meta-Analysis

Being overweight is associated with pregnancy-related disorders such as gestational diabetes mellitus (GDM), hypertensive disorders of pregnancy (HDP), and excessive maternal weight gain (MWG). Exercise and metformin reduce the risk of these disorders. This network meta-analysis (NMA) aims to compare the effect of metformin and different types of exercise (aerobic, resistance and combined) on the risk of GDM, HDP, and MWG among overweight/obese pregnant women. Medline, EMBASE, Web of Science and Cochrane Library were searched from inception to June 2021. Meta-analyses and NMAs were performed. Sixteen randomized controlled trials were included. In the NMA, aerobic exercise showed an effect on GDM (RR = 0.51, 95% CI = 0.26, 0.97), and metformin a reduction in MWG (MWG = -2.93 kg, 95% CI = -4.98, -0.87). No intervention showed any effect on the reduction of HDP. Our study suggests that aerobic exercise may have the greatest effect in reducing the risk of GDM, and perhaps, the MWG. Strategies should be developed to increase adherence to this type of intervention among overweight women without contraindications. Although metformin could reduce MWG, medicalization of pregnancy in healthy women is not justified with the present results. More research is needed on the effect of the intensity and frequency of exercise sessions and the length of interventions.

Risk of neural tube defects according to maternal body mass index: a systematic review and meta-analysis

INTRODUCTION

The aim of our systematic review and meta-analysis was to evaluate the risk of neural tube defects (NTDs) according to the pre-pregnancy body mass index.

MATERIALS AND METHODS

Electronic databases were searched (MEDLINE, EMBASE, Web of Sciences, Scopus, ClinicalTrial.gov, OVID, and Cochrane Library). Selection criteria included prospective and retrospective cohort studies reporting the prevalence of fetal NTDs in obese, overweight, and underweight pregnant women. Odds ratios (ORs) comparing risk among these subsets of pregnancies with normal weight mothers were determined with 95% confidence intervals (CI). The evaluated outcome was the association between maternal underweight, overweight, and obesity and the risk of NTDs.

RESULTS

We included ten studies published between 2000 and 2017, including underweight, overweight, and obese pregnant women with fetal NTD (cases) and pregnant women with recommended BMI with fetal NTD (controls). Compared with normal BMI women, obese mothers were at significantly higher risk of fetal NTDs (0.53 vs. 0.33%; OR 1.62 95% CI 1.32-1.99, p < .0001), while no difference for the risk of NTDs was found when comparing overweight (0.34 vs. 0.32%; OR 1.09 95% CI 0.92-1.3, p = .3) and underweight (0.65 vs. 0.24%; OR 1.34 95% CI 0.73-2.47, p = .34) with normal weight pregnant women.

DISCUSSION

Obese pregnant women are at significantly higher risk NTDs, while no significant difference has been found in overweight and underweight pregnant women. Key message Obese pregnant women are at significantly higher risk of NTDs, such as spina bifida compared with normal weight women. No difference was found when comparing overweight and underweight with normal weight women.

Impact of metformin treatment during pregnancy on maternal outcomes: a systematic review/meta-analysis

We systematically assessed the impact of metformin treatment on maternal pregnancy outcomes. PubMed, Ovid Embase, Medline, Web of Science, ClinicalTrials.gov and Cochrane databases were systematically searched (inception-1st February 2021). Randomised controlled trials reporting pregnancy outcomes in women randomised to metformin versus any other treatment for any indication were included. Outcomes included gestational weight gain (GWG), pre-eclampsia, gestational hypertension, preterm birth, gestational age at delivery, caesarean section, gestational diabetes, glycaemic control, and gastrointestinal side-effects. Two independent reviewers conducted screening, with a third available to evaluate disagreements. Risk-of-bias and GRADE assessments were conducted using Cochrane Risk-of-Bias and GRADE-pro software. Thirty-five studies (n = 8033 pregnancies) met eligibility criteria. GWG was lower in pregnancies randomised to metformin versus other treatments (1.57 kg ± 0.60 kg; I₂ = 86%, p < 0.0001), as was likelihood of pre-eclampsia (OR 0.69, 95% CI 0.50-0.95; I₂ = 55%, p = 0.02). The risk of gastrointestinal side-effects was greater in metformin-exposed versus other treatment groups (OR 2.43, 95% CI 1.53-3.84; I₂ = 76%, p = 0.0002). The risk of other maternal outcomes assessed was not significantly different between metformin-exposed versus other treatment groups. Metformin for any indication during pregnancy is associated with lower GWG and a modest reduced risk of pre-eclampsia, but increased gastrointestinal side-effects compared to other treatments.

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.

The Effect of Metformin on Thyroid-Associated Serum Hormone Levels and Physiological Indexes: A Meta-Analysis

BACKGROUND

Many diseases can be treated with metformin. People with serum thyrotropin (TSH) levels higher than 10 mIU/L are at a risk of cardiovascular events. Some studies have suggested that metformin can lower serum TSH levels to a subnormal level in patients with hyperthyrotropinaemia or hypothyroidism.

OBJECTIVE

The objective of this analysis is to evaluate the effect of metformin treatment on serum TSH, free triiodothyronine (FT3), and free thyroxine (FT4) levels and other associated physiological indices.

METHODS

A comprehensive search using the PubMed, EMBASE, Web of Science and Cochrane Central databases was undertaken for controlled trials on the effect of metformin on serum TSH, FT3, and FT4 levels and associated physiological indices. The primary outcome measures were serum TSH, FT3 and FT4 levels, thyroid size, thyroid nodule size, blood pressure, heart rate, body weight, and body mass index (BMI). The final search was conducted in April 2019.

RESULTS

Six RCTs were included. A total of 494 patients met the inclusion criteria. Metformin treatment did not significantly lower the serum TSH levels at 3 or 6 months but did at 12 months. Moreover, forest plots also suggested that metformin can significantly lower the serum TSH levels in patients with normal thyroid function but cannot statistically change the serum TSH levels in patients with abnormal thyroid function. In addition, metformin treatment clearly lowered the serum FT3 levels and had no significant effect on serum FT4 levels. Lastly, metformin cannot significantly change the systolic blood pressure (SBP) or BMI but can clearly increase the diastolic blood pressure (DBP).

CONCLUSION

Metformin treatment can significantly lower the serum TSH levels, and this effect was much clearer after a 12-month treatment duration and in people with normal thyroid function. However, metformin cannot significantly change the serum FT4 levels or lower serum FT3 levels in people with non-thyroid cancer diseases. In addition, metformin can significantly increase DBP, but it has no clear effect on SBP or BMI.