In this presentation, I review the essential elements of economic analyses of health care programs; the screening tests, interventions, and health outcomes associated with gestational diabetes (GDM); and the cost-effectiveness of screening and interventions for GDM. The cost-effectiveness of screening programs and interventions depend on the comparator (usual care vs. no screening or treatment), the perspective (healthcare sector vs. society), and the time horizon. In general, screening is cost-effective or even cost-saving compared to no screening when GDM is prevalent, screening detects a large proportion of high-risk women, adverse outcomes of GDM are common, and treatment improves outcomes. IADPSG screening criteria are cost-effective compared to Carpenter-Coustan criteria if the analysis adopts a longer time horizon. Key variables that make screening and interventions more cost-effective include high GDM prevalence and poor GDM outcomes; less screening and intervention in the comparison group; high uptake, good detection, and low cost of screening; good effectiveness and low cost of intervention; high incidence of maternal T2DM; good effectiveness and low cost of postpartum interventions; longer time horizon; and higher willingness to pay.