Pregnancy in women with pre-existing type 1 or type 2 diabetes (T1D, T2D) is associated with increased risk of complications, largely driven by maternal glucose control. Hormonal changes during pregnancy make glucose management more challenging. Physical activity (PA) may improve glucose control and reduce complications; however, little is known about PA patterns in this population and no pregnancy-specific PA guidance exists for women with pre-existing diabetes. Understanding the behaviours and experiences of both pregnant women and the healthcare professionals (HCPs) who support them is needed to inform evidence-based guidance.

This mixed-methods study comprises three sub-studies. The first will recruit 175 pregnant women (75 with T1D and 100 with T2D) who will complete three 7-day monitoring periods, one per trimester. PA will be assessed using wrist-worn accelerometers and exercise diaries, dietary intake via remote food photography, and corresponding continuous glucose monitor and diabetes-related well-being data will be collected.

The second involves a subsample of ~16 women participating in focus groups to explore experiences of being physically active during pregnancy.

The third invites ~100 HCPs involved in diabetes in pregnancy care to complete an online survey, ~10 HCPS will take part in an optional interview about their experiences of providing PA guidance.

The primary outcome is the change in PA across pregnancy. Secondary outcomes include associations between PA, glucose metrics, diet and diabetes-related well-being, and qualitative themes relating to experiences of women and HCP. Quantitative data will be analysed using multilevel modelling and regression analysis, and qualitative data using reflexive thematic analysis.

Ethical approval was granted by the East Midlands Nottingham 1 Research Ethics Committee (25/EM/0190) and University of Exeter Public Health and Sport Sciences ethics committee. Findings will be disseminated through peer-reviewed publications and conference presentations.