The impact on pregnancy outcomes of late-onset gestational diabetes mellitus diagnosed during the third trimester: A systematic review and meta-analysis

Background: Evidence is inconsistent regarding the impact of late gestational diabetes mellitus (GDM) on perinatal outcomes. Objectives: To evaluate associations of GDM diagnosed in the third trimester (late GDM) with adverse obstetric and neonatal outcomes. Search Strategy: We searched Embase, Medline, and Web of Science from January 1, 1990 to June 16, 2022, for observational studies. Selection Criteria: Late GDM was defined as a de novo diagnosis, i.e. after a negative screening for diabetes in the second trimester, and at later than 28 weeks of pregnancy. Data Collection and Analysis: Each abstract and full-text article was independently reviewed by the same two authors. Quality was assessed with the use of the Newcastle-Ottawa Scale. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random effects model. Main Results: Twelve studies were identified as meeting the inclusion criteria, including 3103 patients (571 with late GDM and 3103 controls). Incidences of shoulder dystocia (OR 1.57, 95% CI 1.02–2.42, P = 0.040), 5-minute Apgar score <7 (OR 1.80, 95% CI 1.14–2.86, P = 0.024), cesarean delivery (OR 1.98, 95% CI 1.51–2.60, P < 0.001), and emergent cesarean delivery (OR 1.57, 95% CI 1.02–2.40, P = 0.040) were significantly higher among women with late GDM than among the controls. The groups showed similarity in the rates of fetal macrosomia, large-for-gestational-age fetuses, neonatal hypoglycemia, and hypertensive disorders of pregnancy. Conclusions: This meta-analysis showed associations of late GDM with increased adverse perinatal outcomes. Prospective studies should evaluate the impact on perinatal outcomes of repeated third-trimester screening for late GDM.