Long-term effects of prenatal exposure to metformin on the health of children based on follow-up studies of randomized controlled trials: a systematic review and meta-analysis

Epidemiology and management of gestational diabetes

Gestational diabetes is defined as hyperglycaemia first detected during pregnancy at glucose concentrations that are less than those of overt diabetes. Around 14% of pregnancies globally are affected by gestational diabetes; its prevalence varies with differences in risk factors and approaches to screening and diagnosis; and it is increasing in parallel with obesity and type 2 diabetes. Gestational diabetes direct costs are US$1·6 billion in the USA alone, largely due to complications including hypertensive disorders, preterm delivery, and neonatal metabolic and respiratory consequences. Between 30% and 70% of gestational diabetes is diagnosed in early pregnancy (ie, early gestational diabetes defined by hyperglycaemia before 20 weeks of gestation). Early gestational diabetes is associated with worse pregnancy outcomes compared with women diagnosed with late gestational diabetes (hyperglycaemia from 24 weeks to 28 weeks of gestation). Randomised controlled trials show benefits of treating gestational diabetes from 24 weeks to 28 weeks of gestation. The WHO 2013 recommendations for diagnosing gestational diabetes (one-step 75 gm 2-h oral glucose tolerance test at 24-28 weeks of gestation) are largely based on the Hyperglycemia and Adverse Pregnancy Outcomes Study, which confirmed the linear association between pregnancy complications and late-pregnancy maternal glycaemia: a phenomenon that has now also been shown in early pregnancy. Recently, the Treatment of Booking Gestational Diabetes Mellitus (TOBOGM) trial showed benefit in diagnosis and treatment of early gestational diabetes for women with risk factors. Given the diabesity epidemic, evidence for gestational diabetes heterogeneity by timing and subtype, and advances in technology, a life course precision medicine approach is urgently needed, using evidence-based prevention, diagnostic, and treatment strategies.

Metformin Versus Insulin for Gestational Diabetes: Cognitive and Neuropsychological Profiles of Children Aged 9 years

OBJECTIVE

We compared cognitive profile and neuropsychological performance in 9-year-old offspring of mothers who were treated with metformin or insulin for gestational diabetes mellitus (GDM).

METHODS

A total of 172 children whose mothers were randomly assigned to receive either metformin or insulin for GDM were studied at the age of 9 years. Of these children, 127 were from Turku, Finland (63 metformin and 64 insulin), and 45 from Oulu, Finland (19 metformin and 26 insulin). Clinical and demographic background characteristics were obtained at enrolment, birth, and 9-year follow-up. Cognitive profiles were examined at age 9 years with the Wechsler Intelligence Scale for Children. Neuropsychological functions were examined with 2 subtests of the Developmental Neuropsychological Assessment test battery assessing comprehension of instructions and narrative memory, Trail Making Test assessing attention and with Behavioral Rating Inventory of Executive Functioning, including parent-rated and teacher-rated evaluations. Academic functioning was studied with reading fluency subtest of the Screening test for reading, writing, and calculus for first to sixth grades and information about educational support received at school reported by parents.

RESULTS

The cognitive profiles, including indexes of verbal comprehension, perceptual reasoning, working memory, and processing speed, did not differ significantly between metformin-treated and insulin-treated groups. Significant differences were not found between the treatment groups in assessed neuropsychological functions, reading fluency, or received level of support at school.

CONCLUSION

Cognitive and neuropsychological outcomes were similar in 9-year-old children whose mothers had either metformin or insulin treatment of GDM.

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.

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.

Clinical management of pregnancy in women with polycystic ovary syndrome: An expert opinion

Polycystic ovary syndrome (PCOS) is associated with a higher risk for pregnancy and birth complications according to the specific features associated with PCOS. The features include obesity before and during pregnancy, hyperandrogenism, insulin resistance, infertility, cardiometabolic risk factors, and poor mental health. PCOS is not often recognized as a risk factor for poor pregnancy and birth outcomes in pregnancy care guidelines, while its associated features are. Pregnancy-related risk profile should ideally be assessed for modifiable risk factors (e.g., lifestyle and weight management) at preconception in women with PCOS. Hyperglycaemia should be screened using a 75-g oral glucose tolerance test at preconception or within the first 20 weeks of pregnancy if it has not been performed at preconception and should be repeated at 24-28 weeks of pregnancy. In the absence of evidence of benefit for strategies specific to women with PCOS, the international evidence-based guidelines for the assessment and management of PCOS recommend screening, optimizing, and monitoring risk profile in women with PCOS (at preconception, during and postpregnancy) consistent with the recommendations for the general population. Recommended factors include blood glucose, weight, blood pressure, smoking, alcohol, diet, exercise, sleep and mental health, emotional, and sexual health among women with PCOS. The guidelines recommend Metformin in addition to lifestyle for assisting with weight management and improving cardiometabolic risk factors, particularly in those with overweight or obesity. Letrozole is considered the first-line pharmacological treatment for anovulatory infertility in PCOS. Individualized approach should be considered in the management of pregnancy in PCOS.

Neurodevelopmental outcomes of infants of diabetic mothers

With the increase of the incidence of pre-pregnancy diabetes mellitus and gestational diabetes mellitus, the number of infants of diabetic mothers (IDMs) are increasing year by year. IDMs may be associated with poor perinatal outcomes and may have a negative impact on neurodevelopment, but there are relatively few studies on the neurodevelopmental outcomes of IDMs. This article reviews the relevant literature and summarizes the neurodevelopmental outcomes of IDMs from the aspects of sensory and perception, motor, language, intellectual development, neuropsychiatric disorders, neurological examination and drug effect, so as to provide reference for clinical work. Citation.

Maternal PCOS status and metformin in pregnancy: Steroid hormones in 5-10 years old children from the PregMet randomized controlled study

Objective

Polycystic ovary syndrome (PCOS) is a common endocrine disorder, with potential effects on offspring both genetically and through altered intrauterine environment. Metformin, which ameliorate hormonal disturbances in non-pregnant women with PCOS is increasingly used in pregnancy. It passes the placenta, and the evidence on potential consequences for offspring endocrine development is scarce. We explore the potential effects of maternal PCOS status and intrauterine metformin exposure on offspring steroid hormone levels.

Design

This is a follow-up study of 5–10 years old children from the PregMet-study–a randomized controlled trial comparing metformin (2000 mg/day) to placebo during PCOS pregnancies. Of the 255 children invited, 117 (46%) were included.

Methods

There was no intervention in this follow-up study. Outcomes were serum levels of androstenedione, testosterone, SHBG, cortisol, 17-hydroxyprogesterone, 11-deoxycortisol and calculated free testosterone converted to gender-and age adjusted z-scores from a Norwegian reference population. These were compared in i) placebo-exposed children versus children from the reference population (z-score zero) by the deviation in z-score by one-sample t-tests and ii) metformin versus placebo-exposed children by two-sample t-tests. Holm-Bonferroni adjustments were performed to account for multiple endpoints.

Results

Girls of mothers with PCOS (n = 30) had higher mean z-scores of androstenedione (0.73 (95% confidence interval (CI) 0.41 to 1.06), p<0.0001), testosterone (0.76 (0.51 to 1.00), p<0.0001), and free testosterone (0.99 (0.67 to 1.32), p<0.0001) than the reference population. Metformin-exposed boys (n = 31) tended to have higher 11-deoxycortisol z-score than placebo-exposed boys (n = 24) (mean difference 0.65 (95% CI 0.14–1.17), p = 0.014).

Conclusion

Maternal PCOS status was associated with elevated androgens in 5- to 10-year-old daughters, which might indicate earlier maturation and increased risk of developing PCOS. An impact of metformin in pregnancy on steroidogenesis in children born to mothers with PCOS cannot be excluded. Our findings need confirmation in studies that include participants that have entered puberty.

Improvement Effect of Metformin on Female and Male Reproduction in Endocrine Pathologies and Its Mechanisms

Metformin (MF), a first-line drug to treat type 2 diabetes mellitus (T2DM), alone and in combination with other drugs, restores the ovarian function in women with polycystic ovary syndrome (PCOS) and improves fetal development, pregnancy outcomes and offspring health in gestational diabetes mellitus (GDM) and T2DM. MF treatment is demonstrated to improve the efficiency of in vitro fertilization and is considered a supplementary drug in assisted reproductive technologies. MF administration shows positive effect on steroidogenesis and spermatogenesis in men with metabolic disorders, thus MF treatment indicates prospective use for improvement of male reproductive functions and fertility. MF lacks teratogenic effects and has positive health effect in newborns. The review is focused on use of MF therapy for restoration of female and male reproductive functions and improvement of pregnancy outcomes in metabolic and endocrine disorders. The mechanisms of MF action are discussed, including normalization of metabolic and hormonal status in PCOS, GDM, T2DM and metabolic syndrome and restoration of functional activity and hormonal regulation of the gonadal axis.

Metformin use in obese mothers is associated with improved cardiovascular profile in the offspring

BACKGROUND

Maternal obesity increases the risk for pregnancy complications and adverse neonatal outcome and has been associated with long-lasting adverse effects in the offspring, including increased body fat mass, insulin resistance, and increased risk for premature cardiovascular disease. Lifestyle interventions in pregnancy have produced no or modest effects in the reduction of adverse pregnancy outcomes in obese mothers. The Metformin in Obese Pregnant Women trial was associated with reduced adverse pregnancy outcomes and had no effect on birthweight. However, the long-term implications of metformin on the health of offspring remain unknown.

OBJECTIVE

The purpose of this study was to assess whether prenatal exposure to metformin can improve the cardiovascular profile and body composition in the offspring of obese mothers.

STUDY DESIGN

In 151 children from the Metformin in Obese Pregnant Women trial, body composition, peripheral blood pressure, and arterial pulse wave velocity were measured. Central hemodynamics (central blood pressure and augmentation index) were estimated with the use of an oscillometric device. Left ventricular cardiac function and structure were assessed by echocardiography.

RESULTS

Children were 3.9±1.0 years old, and 77 of them had been exposed to metformin prenatally. There was no significant difference in peripheral blood pressure, arterial stiffness, and body composition apart from gluteal and tricep circumferences, which were lower in the metformin group (P<.05). The metformin group, compared with the placebo group, had lower central hemodynamics (mean adjusted decrease, -0.707 mm Hg for aortic systolic blood pressure, -1.65 mm Hg for aortic pulse pressure, and -2.68% for augmentation index; P<.05 for all) and lower left ventricular diastolic function (adjusted difference in left atrial area, -0.525 cm², in isovolumic relaxation time, -0.324 msec, and in pulmonary venous systolic wave, 2.97 cm/s; P<.05 for all). There were no significant differences in metabolic profile between the groups.

CONCLUSION

Children of obese mothers who were exposed prenatally to metformin, compared with those who were exposed to placebo, had lower central hemodynamic and cardiac diastolic indices. These results suggest that the administration of metformin in obese pregnant women potentially may have a beneficial cardiovascular effect for their offspring.

Current Resources for Evidence-Based Practice, July 2020

An extensive review of new resources to support the provision of evidence-based care for women and infants. The current column includes a discussion of whether it is ethical not to offer doula care to all women, and commentaries on reviews focused on folic acid and autism spectrum disorder, and timing of influenza vaccination during pregnancy.

Role of metformin in epigenetic regulation of placental mitochondrial biogenesis in maternal diabetes

Adverse maternal environments, such as diabetes and obesity, impair placental mitochondrial function, which affects fetal development and offspring long-term health. The underlying mechanisms and effective interventions to abrogate such effect remain unclear. Our previous studies demonstrated impaired mitochondrial biogenesis in male human placenta of diabetic mothers. In the present studies, epigenetic marks possibly related to mitochondrial biogenesis in placentae of women with diabetes (n = 23) and controls (n = 23) were analyzed. Effects of metformin were examined in human placental explants from a subgroup of diabetic women and in a mouse model of maternal high fat diet feeding. We found that maternal diabetes was associated with epigenetic regulation of mitochondrial biogenesis in human placenta in a fetal sex-dependent manner, including decreased histone acetylation (H3K27 acetylation) and increased promoter methylation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). In male placenta, the levels of H3K27 acetylation and PGC-1α promoter methylation correlated significantly with the activity of AMP-activated protein kinase (AMPK). Metformin treatment on male diabetic placental explant activated AMPK and stimulated PGC-1α expression, concomitant with increased H3K27 acetylation and decreased PGC-1α promoter methylation. In vivo, we show that maternal metformin treatment along with maternal high fat diet significantly increased mouse placental abundance of PGC-1α expression and downstream mitochondrial transcription factor A (TFAM) and inhibited maternal high fat diet-impaired placental efficiency and glucose tolerance in offspring. Together, these findings suggest the capability of metformin to stimulate placental mitochondrial biogenesis and inhibit the aberrant epigenetic alterations occurring in maternal diabetes during pregnancy, conferring protective effects on offspring.