Late-Onset Diagnosis of Gestational Diabetes After Normal Mid-Pregnancy Screening in Women with Large for Gestational Age or Polyhydramnios: A Systematic Review and Meta-Analysis.

Abstract

Objective: To determine the detection rate of late-onset gestational diabetes mellitus (GDM) and associated perinatal outcomes in women with normal mid-pregnancy glucose screening who undergo repeat oral glucose tolerance testing (OGTT) due to suspected large-for-gestational-age (LGA) fetuses or polyhydramnios.

Data sources: We systematically searched PubMed/MEDLINE, Embase, Web of Science, and the Cochrane Library for studies published from January 2010 to November 2024.

Study eligibility criteria: We included cohort studies reporting late GDM detection rates in women with documented normal mid-pregnancy glucose testing (negative glucose challenge test or normal 75g OGTT at 24-28 weeks) who underwent repeat OGTT after 28 weeks due to sonographic findings of suspected LGA or polyhydramnios. We excluded studies of women with pre-existing diabetes, those lacking documented normal mid-pregnancy screening, and those examining routine late testing without specific clinical indication.

Study appraisal and synthesis methods: Study quality was assessed using the Newcastle-Ottawa Scale. Pooled detection rates with 95% confidence intervals were calculated using random-effects meta-analysis. Subgroup analyses were performed by clinical indication, timing of testing, initial screening method (two-step vs one-step), and maternal BMI. Perinatal outcomes were compared using pooled odds ratios calculated with the Mantel-Haenszel method.

Results: Six cohort studies including 2,166 women met inclusion criteria. The pooled detection rate was 15.0% (95% CI: 9.9-21.0%; I²=91%). Detection rates varied significantly by indication: suspected LGA 20.8% (95% CI: 17.4-24.6%) vs. isolated polyhydramnios 4.8% (95% CI: 2.0-10.8%). Women with late-onset GDM had significantly higher rates of neonatal hypoglycemia (OR 1.82; 95% CI: 1.18-2.81), overall cesarean delivery (OR 2.00; 95% CI: 1.47-2.72), elective cesarean for LGA/macrosomia (OR 3.37; 95% CI: 2.01-5.64), emergent cesarean (OR 1.64; 95% CI: 1.05-2.57), and induction of labor (OR 2.27; 95% CI: 1.32-3.89). Macrosomia by birth weight and LGA at delivery were not significantly elevated.

Conclusions: Late OGTT detects GDM in approximately one in six women with normal mid-pregnancy screening who develop LGA or polyhydramnios. Late-onset GDM is associated with significantly increased neonatal hypoglycemia and cesarean delivery, with the largest effect for elective cesarean for suspected LGA/macrosomia. These findings may inform clinical decision-making regarding repeat glucose testing in the third trimester.