Table 1.

Data collection of the process evaluation of structured supervised exercise training (EXE) and motivational counselling on physical activity (MOT). The dimensions addressed are in relation to implementation (reach, fidelity, and dose) and mechanisms of impact. Quantitative measures of reach were obtained at enrolment from all 220 included participants. Quantitative measures of fidelity, dose delivered and received, and mechanisms of impact were obtained during the intervention period from 87 participants randomised to each intervention group. All qualitative inquiries were obtained from 10 participants in EXE and 10 participants in MOT at the 35th gestational week

Process evaluation dimension	Definition	Quantitative measures	Qualitative inquiries
Reach	Participants included in the FitMum trial	Number of participants included in the FitMum trial and their reasons to participate	What were the reasons to participate?
Fidelity	To what extent the interventions were implemented as intended according to the protocol	How COVID-19 restrictions affected intervention implementation	Not obtained
Dose delivered	The number of intended intervention sessions conducted	How often the sessions were offered	How was intervention accessibility experienced?
			How did participants organise themselves in their everyday life to participate in the interventions?
Dose received	To what extent participants used resources as recommended	To what extent participants adhered to the interventions	What barriers and facilitators did the participants meet towards physical activity?
Mechanisms of impact	How the delivered interventions produced changes	Not obtained	How did the participants experience and perceive the impact of the interventions and what were their physical activity motives?