The function of metformin in endometrial receptivity (ER) of patients with polycyclic ovary syndrome (PCOS): a systematic review and meta-analysis

Abstract

Background This meta-analysis summarizes evidence from studies using metformin (Met) to improve endometrial receptivity (ER) in women with PCOS. Methods Following the PRISMA protocol, we conducted a comprehensive search of academic literature from various databases, including PubMed, EMbase and Cochrane libraries. Studies published in English before Jan 27, 2021, were recruited for primary screening. Data on endometrial thickness (EMT), endometrial artery resistance index (RI), clinical pregnancy rate (CPR) and miscarriage rate (MR) were extracted and analyzed. Results Sixty-two eligible studies that included 6571 patients were evaluated in this meta-analysis. Primary indicators are EMT and endometrial aetery RI; secondary indicators include the clinical pregnancy rate and miscarriage rate. Metformin significantly increased EMT (SMD = 2.04, 95% CI (0.96,3.12),P = 0.0002) and reduced endometrial artery RI compared to the non-Met group (SMD = − 2.83, 95% CI: (− 5.06, − 0.59), P = 0.01). As expected, metformin also improved CPR and reduced MR in PCOS patients as a result, clinical pregnancy rate (risk ratio [RR] = 1.26, 95% CI: 1.11–1.43, P = 0.0003), and miscarriage rate (RR = 0.73, 95% CI:0.58–0.91, P = 0.006). Conclusion Metformin may improve endometrial receptivity (ER) in PCOS patients by increasing EMT and reducing endometrial artery RI. However, the level of most original studies was low, with small sample sizes. More large-scale, long-term RCTs with rigorous methodologies are needed.

The effect of polycystic ovary syndrome on intracytoplasmic sperm injection results in patients with endometriosis

“…Some studies found that preterm delivery was more common in pregnant women with PCOS than in the control group (20,21). However, in others, which compared the results of pregnancy in women with PCOS based on age and weight with the control group, there was no statistically significant relationship between the two groups regarding the prevalence of premature birth (22).…”

Metformin ameliorates endometrial thickness in a rat model of thin endometrium

“…7,8,23 A recent systematic and metaanalysis study concluded that enhanced endometrial thickness and increased blood flow in the endometrium after metformin treatment could be responsible for improved pregnancy rates in metformintreated PCOS women. 9 However, data illustrating direct effects of metformin on endometrium are not conclusive and reports in animal models are relatively scarce. 10,11 Metformin has had a long history of being one of the safest drugs and has shown promising effects beyond type 2 diabetes.…”

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

“…72 A recent meta-analysis of children born to women with GDM or PCOS found that Metformin intake in pregnancy was associated with higher long-term weight in children. 73 Given the positive effects of Metformin in systemic level, 74 it seems rational to use Metformin as a pre-pregnancy treatment for weight management although the role of Metformin on improving pregnancy rate or live birth rate is still debatable 75,76 and the benefit seems to be linked to ovulation induction rather than IVF/ICSI. 77 Nevertheless, the clinical practice should be that when the pregnancy test is positive, Metformin intake is stopped unless the woman has been already diagnosed with DM/GDM and Metformin is part of her care.…”