Exploring the impact of dose in an mHealth intervention to support parents and carers across the first 2000 days of life: Is more always better?

HB4HNEKids is text message program that targets infant feeding practices, child nutrition, physical activity and child development. The text messages are brief (<160 characters) with clickable links to evidence-based ‘online’ videos, fact sheets and websites. The text messages are aligned to the age, stage and developmental milestones of the child across the first 2000 days and for the first 12 months are tailored to the infant feeding status (e.g. breastfeeding, mixed feeding or formula feeding) of the participants. From 1-2 years content aligns with family health and wellbeing, as well as the promotion of healthy eating and movement behaviours. The program includes four phases for the first 2 years of the program: Phase 0- day 0 to day 2 (onboarding from child family health clinics) Phase 1- day 3 to 6 months Phase 2- 6-12 months Phase 3- 1-2 years The high dose group received up to 3-4 messages per week in the first month, 2 per week in the second month and 5 per month from 3 months to 2 years. Adherence to the mhealth strategy was monitored via embedded link-click rates and responses to child feeding status messages.