Table 1 Breastfeeding promotion intervention model based on the Society Ecosystems Theory

Macro system

First week after recruitment

Introduction to policies: Collect breastfeeding policy documents in China and present them to pregnant women and co-parents via online images and text, such as the Global Strategy for Infant and Young Child Feeding, 10 Measures to Promote Successful Breastfeeding (2018), Action Plan for Breastfeeding Promotion (2021–2025), Breastfeeding Guidelines for Infants up to the Age of 6 Months, National Nutrition Program (2017–2030), International Code of Marketing of Breast-milk Substitutes, Chinese national and local maternity leave policies.

First week after recruitment

Breastfeeding support facilities: Pregnant women and those responsible for infant care are introduced to local breastfeeding support facilities, such as mother and baby rooms, Baby Friendly Communities and Hospitals.

Recruitment to one month postpartum

To create a good breastfeeding atmosphere: Actively publicize and report the beneficial experience of breastfeeding through an interactive forum in the Ai You Wei WeChat mini-program; encourage pregnant women and mothers with breastfeeding experience to join the forums and share their experiences and feelings.

Mezzo system (Family)

First week after recruitment

Join WeChat mini-program: Invitation to pregnant women and co-parents to join the online platform “Ai You Wei”.

First and second week after recruitment

Breastfeeding lecture combined with theories and skills: Introduce the breastfeeding theory and skills course to pregnant women and co-parents through a combination of online and offline formats. Details of breastfeeding lecture are shown in Table 2.

First and second week after recruitment

Course evaluation: A combination of theory and skills courses to improve breastfeeding knowledge and skills. An online questionnaire at the end of each course assesses the learning of pregnant women and co-parents and provides additional guidance.

Mezzo system (Hospital)

Recruitment to one month postpartum

WeChat group peer support: Establish a WeChat group jointly managed by obstetricians and gynecologists, obstetric nurses, midwives, breastfeeding counselors, and community breastfeeding professionals, and invite pregnant women and those responsible for infant care to join the group chat to obtain consultation after recruitment.

Within 48 h after delivery

Postnatal hands-on instruction: Instruct mothers and infant caregivers in obstetrics wards to experience on-site breastfeeding together; insist on early contact, early suckling, and early initiation of breastfeeding; provide instruction on feeding-related skills during hospitalization, including correct feeding positions, milking techniques, and so on.

Mezzo system (Community)

Seven days, twoweeks and 1-month postpartum

Home visits: Researcher and community members conduct postpartum home visits to mothers to provide guidance and education to mothers and those responsible for the upbringing of infants on breastfeeding, diet, exercise, and rest for new mothers, and to improve mothers’ breastfeeding knowledge and skills.

Delivery to one month postpartum

Group counseling: Provide online group counseling (four sessions) to encourage peer-to-peer communication. Mothers’ meetings are organized with the participation of obstetricians and gynecologists, obstetric nurses and researchers, and group discussions are held for mothers and co-parents, who are encouraged to speak out about their inner feelings during breastfeeding.

Delivery to one month postpartum

Breastfeeding experience sharing: Mothers with breastfeeding experience are invited to share the beneficial experience of breastfeeding online every week (four sessions).

Micro system

Recruitment to one month postpartum

Individual counseling: One-on-one personalized education or guidance throughout the intervention through home visits, phone calls, and online communication for ongoing breastfeeding.