Focus group discussions
After developing the prototype, we conducted three focus group discussions to elicit feedback regarding the designs, push notifications, and library contents and made modifications accordingly before usability testing.The three focus group discussions with mothers at 24–36 weeks gestation (18 mothers) were held for testing the app designs and messages for the intervention group in both hospitals, both primiparas and multiparous mothers. We asked mothers to score each message from 1 (the lowest) to five (the highest) in terms of their preferences. The messages were categorized into four groups (1) Believing breastmilk is the best option for newborns until 6 months (benefits of breastmilk/colostrum to newborn, to mothers, (2) belief in having enough breastmilk for the baby; (3) involving husband, grandmothers, and healthcare providers support for exclusive breastfeeding, and (4) planning for breastfeeding exclusively.User-friendliness of the messages, perceived relevance of messages, trust in messages, understanding of messages, and new information learned were guided for discussion after ranking [Focus group discussions were undertaken in person by a Vietnamese team member who was working on maternal and child health with experience in both quantitative and qualitative research.