Early-onset gestational diabetes mellitus and secondary maternal and neonatal complications: A systematic review and meta-analysis

Early-onset gestational diabetes mellitus (eGDM) is a distinct phenotype with insulin resistance and adverse metabolic profiles, but its association with secondary maternal and neonatal complications remains unclear. We aimed to evaluate this association compared with late-onset GDM (LGDM). PubMed, EMBASE, Cochrane Central, Web of Science, and CINAHL were searched up to April 20, 2026. Observational studies and secondary analyses of randomised controlled trials comparing eGDM with LGDM were included. Outcomes comprised hypertensive disorders, postpartum haemorrhage, stillbirth, congenital malformations, small for gestational age (SGA), macrosomia, respiratory distress syndrome (RDS), shoulder dystocia, and neonatal hypoglycaemia. Random-effects meta-analysis was performed. Thirty-two studies (113,889 pregnancies) were included. eGDM was associated with higher odds of hypertensive disorders (OR 1.36, 95% CI 1.10–1.69) and stillbirth (OR 2.63, 95% CI 1.75–3.95). No significant associations were observed for congenital malformations, SGA, macrosomia, RDS, shoulder dystocia, or neonatal hypoglycaemia. Heterogeneity was substantial for several outcomes (I² 55.7%–75.0%). GRADE certainty was moderate for stillbirth and SGA, and low for others. eGDM is associated with higher odds of gestational hypertension/preeclampsia and stillbirth compared with LGDM, but not with most other secondary complications. The lack of standardized diagnostic criteria across studies warrants cautious interpretation. These findings support early risk-stratified screening in high-risk women and intensified antenatal surveillance, including blood pressure monitoring and fetal assessment.