The Impact of Dose in an mHealth Intervention to Support Parents and Carers Via Healthy Beginnings for Hunter New England Kids Program: Pragmatic Randomized Controlled Trial.

Background: The dose of mobile health (mHealth) interventions can influence participant engagement, acceptability, and overall impact. However, few mHealth interventions have explored this dose-response relationship.

Objective: This study aims to explore how dose influences the acceptability, engagement, cost, and impact on infant feeding status of a parent-targeted mHealth text messaging program which aims to enhance child health, including breastfeeding exclusivity and duration.

Methods: This pragmatic randomized controlled trial was conducted from October 2021 to May 2024. The Healthy Beginnings for Hunter New England Kids (HB4HNEKids) program provides- text messages aimed to support parents and carers and their children by providing evidence-based preventive health information across the first 2000 days. Participants were enrolled in HB4HNEKids from 5 Child and Family Health Services in the Hunter New England region of New South Wales, Australia, and randomized into either a high-dose or low-dose text message group for the first 2 years of the pilot program. Dose refers to the quantity and frequency of text messages sent to participants. Participants in the high-dose text message group received an average of 111-121 text messages, and the low-dose text message group received 80-82 text messages across the 2 years. Outcomes of interest included acceptability, engagement, cost, and infant feeding status in relation to dose. Engagement with the messages was determined using click rates and program opt-out rates. Participant acceptability was assessed via a brief survey. Impact on infant feeding status (ie, breastfeeding, formula feeding, or mixed feeding) was determined by participants reporting their feeding status at several time points across the program. Cost was determined by assessing the per participant and total cost of sending text messages for each dose group across the 2-year period.

Results: There were no statistically significant differences in click rates between high or low-dose text message groups. In the first 6 months, significantly more participants opted out of the high-dose text message group (191/2724; 7%) compared to the low-dose (108/2812; 3.8%; P<.001). In terms of program acceptability, 183 out of 214 (85.5%) participants of the high-dose and 228 out of 252 (90.5%) participants of the low-dose text message group were satisfied with the frequency of text messages. In addition, 188 out of 215 (87%) participants of high-dose and 220 out of 255 (86%) participants of low-dose text message group indicated they would recommend the program to other caregivers. The average per participant and total cost to the health service for sending messages was lower in the low-dose group (A$9.32 per participant and A$15,271.48 total; A$1 is approximately equal to US $0.68) compared to the high-dose text message group (A$12.96 per participant and A$21,241.44 total).

Conclusions: The HB4HNEKids program demonstrated positive outcomes including high acceptability across both groups and no impact on infant feeding status, irrespective of dose. Given the higher opt-out rates and message costs in the high-dose text message group, a lower dose is likely more scalable for future use.