Abstract Disclosure: A. Al Nofal: None. K. Benkhadra: None. M. Nduwimana: None. A. Mohammad: None. A. Abbas: None. Z. Wang: None. M. Murad: None. Background: Hybrid closed-loop (HCL) systems for automated insulin delivery are increasingly used in diabetes management. However, their safety and efficacy in pregnant women with pre-existing type 1 diabetes remain uncertain. Aim: To assess the safety and effectiveness of HCL systems in pregnant women with pre-existing type 1 diabetes compared to current standard of care. Methods: A comprehensive search of several databases was conducted from inception to January 3rd, 2024. Pairs of independent reviewers screened abstracts. Abstracts included by at least one reviewer were reviewed in full text by a pair of independent reviewers. The DerSimonian and Laird random effects model with the Hartung-Knapp-Sidik-Jonkman method was used to pool effect sizes across the included studies. Results: Five randomized controlled trials (RCTs) with 274 pregnant women with type I diabetes met the inclusion criteria. Our meta-analysis showed no significant difference between HCL and standard of care regarding overall time in range (TIR), time above range (TAR), and time below range (TBR). However, overnight, women using HCL showed significantly higher TIR (mean difference: 10.18%, CI 7.42-12.94%) and lower TBR (mean difference: -0.67%, CI -0.91 to -0.43%) compared to those using standard care. Additionally, there were no significant differences between HCL and standard of care in term of LGA, SGA, neonatal hypoglycemia, and maternal severe hypoglycemia or hyperglycemia. Conclusion: HCL systems for management of pre-existing type I diabetes during pregnancy are associated with similar outcomes without increased risk of complications when compared to standard of care. This is derived from limited number of RCTs with low risk of bias but significant imprecision, which warrant low confidence. Presentation: Sunday, July 13, 2025