In-utero exposure to metformin for type 2 diabetes or polycystic ovary syndrome: A prospective comparative observational study

Efficacy and safety of metformin during pregnancy: an update

During the last decades, gestational diabetes mellitus (GDM) prevalence has been on the rise. While insulin remains the gold standard treatment for GDM, metformin use during pregnancy is controversial. This review aimed to comprehensively assess the available data on the efficacy and safety of metformin during pregnancy, both for the mother and the offspring. Metformin has been validated for maternal efficacy and safety, achieving comparable glycemic control with insulin. Additionally, it reduces maternal weight gain and possibly the occurrence of hypertensive disorders. During the early neonatal period, metformin administration does not increase the risk of congenital anomalies or other major adverse effects, including lower APGAR score at 5 min, neonatal intensive care unit admissions, and respiratory distress syndrome. Several studies have demonstrated a reduction in neonatal hypoglycemia. Metformin has been associated with an increase in preterm births and lower birth weight, although this effect is controversial and depends on the indication for which it was administered. Evidence indicates possible altered fetal programming and predisposition to childhood obesity and metabolic syndrome during adulthood after use of metformin in pregnancy. With critical questions still requiring a final verdict, ongoing research on the field must be conducted.

Major malformations risk following early pregnancy exposure to metformin: a systematic review and meta-analysis

Metformin is considered as first-line treatment for type 2 diabetes and an effective treatment for polycystic ovary syndrome (PCOS). However, evidence regarding its safety in pregnancy is limited. We conducted a systematic review and meta-analysis of major congenital malformations (MCMs) risk after first-trimester exposure to metformin in women with PCOS and pregestational diabetes mellitus (PGDM). Randomized controlled trials (RCTs) and observational cohort studies with a control group investigating risk of MCM after first-trimester pregnancy exposure to metformin were searched until December 2021. ORs and 95% CIs were calculated separately according to indications and study type using Mantel-Haenszel method; outcome data were combined using random-effects model. Eleven studies (two RCTs; nine observational cohorts) met the inclusion criteria: four included pregnant women with PCOS, four included those with PGDM and three evaluated both indications separately and were considered in both indication groups. In PCOS group, there were two RCTs (57 exposed, 52 control infants) and five observational studies (472 exposed, 1892 control infants); point estimates for MCM rates in RCTs and observational studies were OR 0.93 (95% CI 0.09 to 9.21) (I²=0%; Q test=0.31; p value=0.58) and OR 1.35 (95% CI 0.37 to 4.90) (I²=65%; Q test=9.43; p value=0.05), respectively. In PGDM group, all seven studies were observational (1122 exposed, 1851 control infants); the point estimate for MCM rates was OR 1.05 (95% CI 0.50 to 2.18) (I²=59%; Q test=16.34; p value=0.01). Metformin use in first-trimester pregnancy in women with PCOS or PGDM do not meaningfully increase the MCM risk overall. However, further studies are needed to characterize residual safety concerns.

The use of metformin in women with polycystic ovary syndrome: an updated review

PURPOSES

Polycystic ovary syndrome (PCOS) is a major cause of female infertility, being present in up to 20% of women of childbearing age. Insulin resistance (IR) plays an important role in the pathophysiology of PCOS; therefore, its treatment may benefit women with the syndrome. The main drug used for IR management is metformin (MT). We aim to review the literature on the use of metformin in women with PCOS.

METHODS

Using the terms "metformin" and "polycystic ovary syndrome," we conducted a search the PubMed, EMBASE, and Google Scholar databases. The research was restricted to articles published in English. Initially, only published meta-analyses were included, in the absence of meta-analyzes, RCT and well-designed prospective studies were used.

RESULTS

Metformin increases success rates and decreases complication rates when used as an adjunctive medication for ovulation induction during low complexity assisted reproduction treatments and during ovarian stimulation for in vitro fertilization in women with PCOS. Evidence about the effect of metformin on fetal and obstetric complication rates is conflicting. Metformin is associated with high incidence of gastrointestinal symptoms; however, serious adverse effects are rare and there is no evidence of teratogenicity.

CONCLUSION

For women with PCOS, metformin is a good adjunctive medication for ovulation induction/stimulation for high and low complexity assisted reproduction therapies. The adverse effects are mostly mild, and there is no risk of teratogenicity, but the risk of long-term complications for the offspring is not yet defined. High heterogeneity of the studies limits extrapolation of findings, and further research is needed to determine which women will benefit most from the medication.

Metformin in pregnancy and risk of adverse long-term outcomes: a register-based cohort study

This study aimed to investigate if maternal pregnancy exposure to metformin is associated with increased risk of long-term and short-term adverse outcomes in the child. RESEARCH DESIGN AND METHODS : This register-based cohort study from Finland included singleton children born 2004-2016 with maternal pregnancy exposure to metformin or insulin (excluding maternal type 1 diabetes): metformin only (n=3967), insulin only (n=5273) and combination treatment (metformin and insulin; n=889). The primary outcomes were long-term offspring obesity, hypoglycemia, hyperglycemia, diabetes, hypertension, polycystic ovary syndrome, and challenges in motor-social development. In a sensitivity analysis, the primary outcomes were investigated only among children with maternal gestational diabetes. Secondary outcomes were adverse outcomes at birth. Analyses were conducted using inverse- probability of treatment weighting (IPTW), with insulin as reference. RESULTS  : Exposure to metformin or combination treatment versus insulin was not associated with increased risk of long-term outcomes in the main or sensitivity analyses. Among the secondary outcomes, increased risk of small for gestational age (SGA) was observed for metformin (IPTW-weighted OR 1.65, 95% CI 1.16 to 2.34); increased risk of large for gestational age, preterm birth and hypoglycemia was observed for combination treatment. No increased risk was observed for neonatal mortality, hyperglycemia, or major congenital anomalies. CONCLUSIONS : This study found no increased long-term risk associated with pregnancy exposure to metformin (alone or in combination with insulin), compared with insulin. The increased risk of SGA associated with metformin versus insulin suggests caution in pregnancies with at-risk fetal undernutrition. The increased risks of adverse outcomes at birth associated with combination treatment may reflect confounding by indication or severity.

Fetal safety of medications used in treating infertility

INTRODUCTION

The medications used in assisted reproduction are given before and during early pregnancy, and hence, they may potentially result in adverse fetal effects. In this review we present an updated account of their fetal safety and discuss methodological challenges in interpretation of existing data.

AREAS COVERED

The fetal safety/risks of clomiphene citrate, aromatase inhibitors, metformin, gonadotropins and progestins are discussed. We searched PubMed, EMBASE, Cochrane, Google, and Google Scholar from inception to 30 April 2020 for publications pertinent to our topic.

EXPERT OPINION

There are several major challenges in studying fetal safety of medications used in assisted reproduction. The fact is that the rates of congenital malformations among infertile women giving birth spontaneously is higher than the rates among healthy women conceiving spontaneously. In most clinical studies of assisted reproduction, the primary endpoint is the success in inducing pregnancy, neglecting to report pregnancy outcome and adverse neonatal event. As an example for this reality, it has been estimated that between 1977 and 2005 around 10 million pregnancies were treated with dydrogesterone (DYD), yet till 2019 only very few studies, with a total sample size of less than 600 were reported with regards to fetal safety.

Hyperandrogenemia and insulin resistance: The chief culprit of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the most common systemic reproductive endocrine diseases, which has a variety of effects on a woman's health. Because of the involvement of multiple pathways and the lack of common clues, PCOS demonstrates multifactorial properties and heterogeneity of symptoms. Recent studies have demonstrated that the core etiology and primary endocrine characteristics of PCOS are hyperandrogenemia (HA) and insulin resistance (IR). HA and IR are the main causes of PCOS and they can interplay each other in the occurrence and development of PCOS. Just because of this, the study about the effects of HA and IR on pathophysiology of various related symptoms of PCOS is very important to understand the pathogenesis of PCOS. This paper reviews the main symptoms of PCOS, including neuroendocrine disorders, reproductive processes, dyslipidemia, obesity, hypertension, nonalcoholic fatty liver disease (NAFLD), and sleep disordered breathing, which seriously affect the physical and mental health of PCOS women. The increasing knowledge of the development pattern of HA and IR in PCOS suggests that changes in diet and lifestyle, and the discovery of potential therapeutic agents may improve PCOS. However, further studies are needed to clarify the mutual influence and relation of HA and IR in development of PCOS. This review provides an overview of the current knowledge about the effects of HA and IR on PCOS.