Table 1.

Core STAR MAMA intervention components and moderating factors evaluated

Domain	What is required for high fidelity	Fidelity assessment questions	Specific outcome	[Data Source]
Core fidelity component assessment
1. System Integration (combining participant registry with intervention delivery platform)	(a) Complete registration and uploading of GDM patient details to ATSM system (after baseline enrolment/randomization) (b) Activation of the ATSM system to initiate intervention delivery (timed to 6 weeks post-partum)	(a) Was the participant-level data integrated into the ATSM system prior to 6 weeks post-partum? (b) Was the STAR MAMA start correctly implemented for the first call to be delivered 6 weeks post-partum?	(a) % of enrolled women in trial at each clinical site, with data uploaded to the ATSM delivery platform (b) % of intervention starts correctly linked to delivery date	[System-generated weekly report]
2. Intervention delivery	Correct ATSM ‘push’ of weekly intervention content to each participant, at a pre-specified time and day, based on participant preferences	Did the ATSM system correctly delivery weekly call content to participants? (a) All the calls were sent as planned (b) Delivery of all intervention weeks (completeness) (c) Delivery of correct sequencing of intervention (alignment with intervention logic for post-partum period/infant development)	(a) % of calls correctly delivered (b) % of participants delivered/not delivered all 20 weeks of calls (c) % of participants with delivered weeks in the correct sequence for all 20 weeks	[System-generated weekly and daily reports]
3. Consistency of intervention delivery over time	Consistency of ATSM ‘push’ of weekly intervention content across the study intervention period	Did the ATSM system result in error clustering? Or were errors spread out over time across weeks and over the study period?	% of participants with an early (weeks 1–5) vs later (≥ week 6) missed week delivery	[System-generated weekly and daily reports]
4. Health coach responsiveness to participant ‘triggers’	Responsiveness of health coaches to participant triggers generated by touch tone responses to calls	Did health coaches call back participants whose daily reports indicated a trigger warranting further follow up?	% of women with at least one documented trigger who subsequently received a health coach initiated call attempt	[System-generated weekly and daily reports] and [Health Coach Database]
Moderating factors
Health coach consistency of outreach over time	Level of fluctuation in call-back attempts over time by health coaches	Did health coaches make call-back attempts consistently over the study intervention period?	% of triggers over time that received an attempted call back	[System-generated weekly and daily reports] and [Health Coach Database]
Language equity: health coach consistency of outreach for participant language and enrolment site	Level of fluctuation in call-back attempts by language or site	Did health coaches make call-back attempts similarly for Spanish and English speaking participants and for enrolment sites?	% of triggers by language, over time, that received an attempted call back	[System-generated weekly and daily reports] and [Health Coach Database]
Language equity: acceptability of the STAR MAMA calls and health coaching package	N/A	How acceptable was the intervention to enrolled women? Would they do it again or refer others?	Levels of acceptability reported at follow-up after the program was over	[Interview data]