Maternal and neonatal outcomes with different screening strategies for gestational diabetes mellitus: a retrospective cohort study.

Objective: To evaluate the effect of an expanded gestational diabetes mellitus (GDM) screening strategy on perinatal outcomes.

Methods: This retrospective cohort study included gravidas screened for GDM at a single academic center. The "before" cohort (estimated due dates (EDD) March 2018-April 2019) was screened using the standard 2-step method. The "after" cohort (EDD November 2019-July 2023) was screened using an expanded strategy that included the potential for GDM diagnosis based on 1-2 weeks of home glucose monitoring following isolated fasting hyperglycemia on the 3-hour glucose tolerance test (GTT). The primary outcomes were primary cesarean delivery (PCD) and neonatal intensive care unit (NICU) admission. Binomial regression and Kruskal Wallis tests were used to compare perinatal outcomes between the two cohorts in the general population and in a subgroup of those with isolated fasting hyperglycemia.

Results: Outcomes for the "before" cohort (n = 1,733) were compared with those in the "after" cohort (n = 6,280). In the general population, A2GDM incidence increased after expansion of the screening protocol (4.8% vs. 6.4%, RR 1.34, 95% CI 1.07-1.69), but PCD and NICU admission rates were unchanged. In the subgroup of patients with isolated fasting hyperglycemia (n = 233), there was a significant increase in the incidence of any GDM (12.5 vs. 46.0%, RR 3.68, 95% CI 1.95-6.93) and A2GDM (8.3% vs. 37.3%, RR 4.47, 95% CI 2.03-9.87). There was no difference in PCD between cohorts, but NICU admission increased significantly in the "after" cohort (8.3% vs 22.4%, RR 2.68, 95% CI 1.18-6.08) in this subgroup.

Conclusion: An expanded approach to GDM diagnosis using home blood glucose monitoring following isolated fasting hyperglycemia on 3-hour GTT was associated with increased A2GDM incidence but no improvements in primary maternal or neonatal outcomes. In the absence of clinical benefit, we do not recommend widespread implementation of this expanded strategy.