A multicentre, randomised controlled trial (the CRISTAL trial), demonstrated the safety and efficacy of MiniMed™ 780G advanced hybrid closed loop (AHCL) therapy during pregnancy, showing improved glycaemic control overnight, less hypoglycaemia, and improved treatment satisfaction compared to standard insulin therapy (SoC, mainly open-loop insulin pump therapy). This study aimed to assess the cost-effectiveness of AHCL, which has a higher initial cost, compared to SoC in pregnant women with type 1 diabetes (T1D). A decision tree model was developed to estimate the cost-effectiveness of AHCL compared to SoC in pregnant women with T1D, covering pregnancy to birth and postpartum hospital discharge (a time horizon of 28 weeks). Total costs per strategy (in 2024 euros, €) were calculated from a healthcare payer perspective. The base-case analysis derived prevalence of pregnancy complications and hospitalisations directly related to diabetes management from the CRISTAL trial. Uncertainty was analysed by exploring multiple scenarios and sensitivity analyses. In the base-case analysis, the cost of using AHCL during pregnancy was estimated at €13,988.75 (95% CI: €12,240 to €16,062) compared to €14,221.33 (95% CI: €12,380 to €16,420) for SoC, indicating cost-savings of €232.57 per individual, alongside the demonstrated clinical benefits of AHCL. The primary cost driver was the AHCL device cost. This cost was offset by savings from shorter and less frequent hospital admissions (mainly due to severe hypoglycaemia and dysregulated diabetes) in the AHCL group compared to SoC. In our probabilistic sensitivity analysis, AHCL was dominant in 73% of the simulated cost-effectiveness pairs. AHCL might be cost-saving compared to SoC for pregnant women with T1D. However, more robust data are needed to assess the potential impact of AHCL therapy on pregnancy and long-term health outcomes. Diabetes Liga Research Fund and Medtronic.