The randomized controlled trial design with one intervention arm (nutrition education and complementary feeding) and one control (usual care) arm (1:1 ratio). will be conducted in the second phase. This trial will be conduct in mothers with children aged under 2 years of age of Nusa Tenggara Barat Province of Indonesia.~Randomization of each participant to the groups will be carried out using Random Allocation Software 1.0 (https://random-allocation-oftware.software.informer.com/1.0/) to intervention or control groups in a 1:1 ratio. The randomization will be performed by a research assistant with no access to participant information and who did not participate in the enrolment process. The permuted block randomization for a block size of four and six will be used in order to maintain an adequate balance in the number of participants allocated to each of the study groups. The person performing the intervention will be blinded to group allocation. Outcome data will be collected by another two blinded research assistants, one for the intervention group and one for the control group. The completed and coded questionnaires will be entered into databases by research assistant who unaware of group allocation.~The eligible participant will include mothers who have children under 2 years of ages with undernutrition categories residences in Lombok Barat or Lombok Tengah District, mothers who are able to speak Bahasa or Sasak languages, mothers who are able to use a telephone. The exclusion criteria will include mothers with impaired cognitive function, and psychiatric diseases, children suffering from severe/chronic diseases, mental retardation, physical disability, and with hospitalization within six months are excluded from participating in this study.~A priori power analysis has been calculated to determine an adequate sample size for the study. Prior data indicates that the application of the health belief model to teach complementary feeding messages in Ethiopia is 56%. Using a level of conﬁdence of .05 and power of 80% the required sample size was 36.85 participants, with the consideration of 10% dropout rate, it was around 40 for one group. In total the investigator will aim for ﬁnal estimate sample size to be recruited is 80.
The randomized controlled trial design with one intervention arm (nutrition education and complementary feeding) and one control (usual care) arm (1:1 ratio). Randomization of each participant to the groups will be carried out using Random Allocation Software 1.0 (https://random-allocation-oftware.software.informer.com/1.0/) to intervention or control groups in a 1:1 ratio. The sample size to be recruited is 80 participants.