Abstract Background Customized and standard automated insulin delivery (AID) systems for use in pregnancies of women with pre-existing type 1 diabetes (T1D) are being developed and tested to achieve pregnancy appropriate continuous glucose monitoring (CGM) targets. Guidance on use of CGM for treatment decisions during pregnancy in the US is limited. Methods Ten pregnant women with pre-existing T1D participated in a trial evaluating at-home use of a pregnancy-specific AID system. Seven-point self-monitoring of blood glucose (SMBG) was compared to the closest sensor glucose (CGM-Dexcom G6) value biweekly to assess safety and reliability based on the 20%/20 mg/dL criteria. Results All participants completed the study with seven participants satisfying the safety and reliability criteria with mean absolute relative difference of 10.3%. Three participants did not fulfill criteria mainly because the frequency of SMBG did not meet requirements. Conclusion Dexcom G6 CGM is safe and accurate in the real world setting for use in pregnant women with pre-existing T1D with reduced SMBG testing as part of a pregnancy specific AID system.