Supplementary Material for: Association between polycystic ovarian syndrome and risk of gestational diabetes mellitus: A meta-analysis

Objectives: The results of studies regarding the association between polycystic ovary syndrome (PCOS) and gestational diabetes mellitus (GDM) are controversial. Design: This meta-analysis was conducted to evaluate the relationship between PCOS and GDM. Methods: English language articles published before July 2021 were included by searching in databases: PubMed, EMBASE, Web of Science, Medline and Google Scholar. All these results were computed using STATA 12.0 software. The random-effects models were used to calculate summary odds ratio (OR) or relative risk (RR) and 95% confidence interval (CI) when the heterogeneity was high; Inversely, the fixed-effects models were used to calculate summary OR/RR and 95% CI when the heterogeneity was low. Results: The present study showed that PCOS was significantly associated with an increased risk of GDM with a random effects model (OR/RR = 2.02, 95% CI 1.74 to 2.34, I2 = 79.5%, p < 0.0001). Subgroup analysis indicated an elevated risk of GDM in PCOS patients in both retrospective and prospective studies (retrospective studies: OR = 1.89, 95% CI 1.62 to 2.20; prospective studies: RR = 2.85, 95% CI 1.77 to 4.60). In addition, subgroup analysis indicated an elevated risk of GDM in PCOS patients in both Caucasian and Asian populations (Caucasian populations: OR/RR = 2.47, 95% CI 1.99 to 3.07; prospective studies: OR/RR = 1.58, 95% CI 1.23 to 2.02). Conclusion: Overall, findings of the meta-analysis showed that women with PCOS have an elevated risk of GDM compared to women without PCOS. Limitations: First, on account of sources of information, the role of several variables including BMI, the severity of GDM and serum lipid level in the association between PCOS and GDM can not be evaluated. Second, only studies published in English and Chinese were included, and the publish bias is impossible to avoid.