Association between gestational diabetes mellitus diagnostic criteria and adverse pregnancy outcomes-a systematic review and meta-analysis of adjusted effect sizes from studies using current diagnostic criteria

Objectives To quantify the association between Gestational Diabetes Mellitus (GDM) and adverse pregnancy outcomes and primarily compare the associations between diagnostic criteria following the International Association of Diabetes and Pregnancy Study Groups (IADPSG) recommendations and non-IADPSG criteria, which use higher blood glucose cut-offs.Design Systematic review and meta-analysis of observational studies using contemporary GDM diagnostic criteria.Data sources PubMed, Scopus, Google Scholar, Cochrane Database of Systematic Reviews and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) were searched for articles published between 2010 and 2023. The search was carried out on 15 May 2023.Eligibility criteria Studies were included if they were observational studies that reported adjusted effect sizes for GDM-related adverse outcomes and compared outcomes between women with and without GDM, used contemporary diagnostic criteria and were conducted after 2010.Data extraction and synthesis Two reviewers independently extracted data and assessed study quality using the MethodologicAl STandards for Epidemiological Research (MASTER) scale. Bias-adjusted inverse variance heterogeneity meta-analysis models were used to synthesise adjusted effect sizes. The same meta-analytic models were used to synthesise the overall OR and their 95% CIs for comparisons of the criteria which followed the IADPSG recommendations to other criteria, mostly with higher blood glucose cut-offs (non-IADPSG).Results We included 30 studies involving 642 355 participants. GDM was associated with higher odds of maternal outcomes, namely; caesarean section (adjusted OR (aOR) 1.24, 95% CI 1.01 to 1.51) and pregnancy-induced hypertension (aOR 1.55, 95% CI 1.03 to 2.34). GDM was associated with higher odds of neonatal outcomes, specifically; macrosomia (aOR 1.38, 95% CI 1.13 to 1.69), large for gestational age (aOR 1.42, 95% CI 1.23 to 1.63), preterm birth (aOR 1.41, 95% CI 1.21 to 1.64), neonatal intensive care unit admission (aOR 1.42, 95% CI 1.12 to 1.78), neonatal hypoglycaemia (aOR 3.08, 95% CI 1.80 to 5.26) and jaundice (aOR 1.47, 95% CI 1.12 to 1.91). Further analyses showed no major differences in adverse pregnancy outcomes between IADPSG and non-IADPSG criteria.Conclusions GDM is consistently associated with adverse pregnancy, maternal and foetal outcomes, regardless of the diagnostic criteria used. These findings suggest no significant difference in risk between lower and higher blood glucose cut-offs used in GDM diagnosis.