Table 1 Definition of the concepts in the ICAMO heuristic

Intervention (I)

Refers to the characteristics of various mHealth interventions such as type of technology, co-interventions, and modalities. In this case, mHealth modality was defined as use of mobile phones and tablets, making use of text, audio, images, short messaging services (SMS), voice SMS, applications accessible via general packet radio service.

Context (C)

Describes conditions required for programme mechanisms to activate or not. Context can be viewed as circumstances that facilitate or constrain mechanisms, including pre-existing individual, organisational, social and cultural conditions, that are external to the interventions [23]. In this case, context is categorised as a) Environmental, which comprises the broad external environment in which interventions are situated, including political, economic, social, technological, legal, and infrastructural environments [2]; and b) Organisational/health systems, which include resources, policies and structures directly related to the unique health facility settings in which mHealth technology is introduced [2].

Actors (A)

Includes individuals, groups, and institutions that play a role in the implementation and uptake of interventions [24]. In this study, actors include pregnant women, mothers and HCPs, including community health workers.

Mechanism (M)

A mechanism refers to causal forces, powers, processes or interactions that generate behavioural change. In realist evaluation terms, mechanisms include choices, perceptions, reasoning and decisions that people make as a result of the resources provided by programmes.

Outcomes (O)

Defined as products of mechanisms activated within specific contexts. Outcomes are anticipated and unanticipated (emergent) consequences of interventions [17].