Aim

This study aims to compare the effect of a breastfeeding promotion intervention model based on the SET versus a usual prenatal and postnatal care program on the EBF rate at 6 months and breastfeeding duration; on improving maternal breastfeeding attitudes, knowledge, and self-efficacy; and on improving maternal and infant health.

Study design and setting

The study is a single-blind, parallel design, randomized controlled trial with an intervention group (IG) and a control group (CG) allocated with a 1:1 randomization ratio that compares the effect of the breastfeeding promotion intervention model based on the SET, which is an IG, with a usual prenatal and postnatal care group, which is a CG (Fig. 2). This research will be conducted from August 2023 to April 2024 in Wuhan, China. Pregnant women will be recruited from August to October 2023 by convenience sampling at the Department of Obstetrics of Hubei Province Maternal and Child Health Hospital. The study protocol in compliance with the Declaration of Helsinki was approved by the Ethics Committee of Medical Research Committee of Medical College of Wuhan University (WHU-LFMD-IRB2023050) and the Hubei Province Maternal and Child Health Hospital (2023IEC070). It has registered in the Chinese Clinical Trial Registry at www.chictr.org.cn (registration number: ChiCTR2300075795).

Fig. 2

Research flow chart. IIFAS Iowa Infant Feeding Attitude Scale, BKQ Breastfeeding Knowledge Questionnaire, BSES-SF Breastfeeding Self-efficacy Seale Short Form, EPDS Edinburgh Postnatal Depression Scale, SSRS Social Support Rating Scale, PAQ Pregnancy-Related Anxiety Questionnaire, PSAS-CN Postpartum Specific Anxiety Scale-Chinese Version

Eligibility criteria

Women who are aged 18 to 36 years, 28 to 35 weeks of gestation, singleton pregnancy, with basic literacy skills and no barriers to communication and able to use a smartphone will be recruited. Participation will be voluntary and informed consent will be obtained; participants can withdraw from the study at any time with no prejudice. Women with serious contraindications to breastfeeding, such as acute infectious diseases, infection with acquired immune deficiency syndrome, syphilis, mammary gland insufficiency, breast surgeries such as mastopexy; or serious mental illness are excluded.

Sample size

The current EBF rate for infants under 6 months of age in China is 34.1% [3]. After the intervention, the rate is expected to increase to 60%, which was required by the National Nutrition Plan (2017–2030) [5]. Sample size was calculated for EBR in 6 months for a two-sided hypothesis test with a power of 90% and a significance level of 0.05. Therefore, according to the following formula, the study requires a minimum sample size of 76 (each group). Considering a 20% lost follow-up rate and 20% withdrawal rate because of failure to participate in the full intervention due to prematurity, a total of 218 participants will be needed for the study.

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Randomization

All patients who consent to participate and who fulfill the inclusion criteria will be randomized. Eligible participants will be randomly assigned to the IG and the CG based on a table of random numbers (https://www.sealedenvelope.com/). Results of random allocation will be placed in an opaque envelope.

Blinding

Allocation details will be placed in opaque and sealed envelopes by a study coordinator and concealed from recruiters, data collectors and the group allocator. After recruitment and baseline data collection, the other study coordinator will open the envelopes and allocated participants. Due to the nature of the intervention, intervention conductors and participants will not be blinded to group allocation. The data collector will be masked to group allocation during data collection and the statistician will also be masked during data analyses.

InterventionsControl group

Participants in the CG will receive usual prenatal and postnatal care. At the same time, they will be contacted by the researchers upon initial enrollment in the study but receive no further guidance and interventions.

Intervention group

The intervention of this study was constructed based on a literature review, qualitative interviews and group discussion. And the feasibility and importance of the intervention program were verified through two rounds of expert consensus based on the Delphi method [25].

Participants in the IG will be offered the breastfeeding promotion intervention model based on the SET. According to the SET, the intervention is designed in three parts: macro system, mezzo system and micro system. (1) Macro system: It mainly refers to the policies, institutions and culture that affect breastfeeding. This study can create a favorable breastfeeding atmosphere through activities such as introducing breastfeeding and childbirth-related policies and actively publicizing and reporting beneficial experiences of breastfeeding promotion. (2) Mezzo system: It refers to a small group of people including pregnant women. Hospitals, communities and families are important places for women throughout pregnancy, delivery and the postpartum period. This study will optimize the breastfeeding promotion intervention of hospital-community-family to achieve information sharing and joint management. Relying on the online WeChat mini program, it will be extended to offline services. (3) Micro system: Maternal individuals, as subjects, are the core of the social ecosystem. This study will provide social support to maternal individuals to reduce the incidence of depression and anxiety, improve the rate of breastfeeding, and promote maternal and child health. Details of the intervention are shown in Tables 1 and 2.

Table 1 Breastfeeding promotion intervention model based on the Society Ecosystems TheoryTable 2 Schedule of prenatal breastfeeding lectures including theories and skillsIntervention personnel training

Prior to the start of the study, the intervention implementers will undergo uniform training and assessment. Criteria for inclusion of intervention implementers include healthcare personnel with (1) intermediate or higher job title, (2) working in obstetrics and gynecology for ≥ 5 years, and (3) basic knowledge of breastfeeding nursing guidance. Training content and methods: (1) lectures on breastfeeding-related theories and skills; (2) self-study and online learning: theoretical knowledge and related materials, such as the Global strategy for infant and young child feeding [1], Guide to infant feeding and nutrition [26], and Breastfeeding guidelines for infants within 6 months of age [27]. (3) simulation scenario: hands-on breastfeeding instruction. Assessment methods: (1) self-assessment: evaluation using the breastfeeding knowledge questionnaire (BKQ); (2) peer assessment: test questions on knowledge of breastfeeding theories and skills; (3) simulation method: simulated lectures and hands-on instruction on breastfeeding.

Data collectionBasic information questionnaire

A researcher-designed questionnaire of socio-demographic information will be used to collect basic information about participants, including gestational age, number of pregnancies, parity, education level, family monthly income, employment status, length of maternity leave, co-parenting members, conception mode at baseline; and delivery mode, weeks of delivery, time of breastfeeding initiation, separation of mother and infant, and presence of comorbidities at 1 month postpartum.

Primary outcome

Breastfeeding rate is the primary outcome in this study. The infant feeding patterns are collected at 1-, 4- and 6-months postpartum. The breastfeeding rate and EBF rate at 1-, 4-, and 6-months postpartum are also calculated.

Secondary outcomesMaternal and neonatal morbidity outcomes

Maternal adverse lactation events include depressed nipples, breast milk stasis, acute mastitis, cracked nipples, breast swelling, breast eczema, and nipple trauma. The health status of infants will be investigated at 1-, 4- and 6-months postpartum by asking the mothers and their co-parents whether infants suffer from any conditions (eczema, anemia, diarrhea, and pneumonia). The height and weight of the infant at birth, 1 month, 4 months, and 6 months will also be investigated by questioning the mothers and co-parents.

Iowa infant feeding attitude scale (IIFAS)

The IIFAS will be used to assess maternal feeding attitude. This scale includes 17 items developed by Mora and colleagues [28]. The items incorporate a five-point Likert scale with categories of “strongly disagree” (1), “disagree” (2), “being neutral” (3), “agree” (4), and “strongly agree” (5). Nine items (numbers 1, 2, 4, 6, 8, 10, 11, 14 ,17) are reverse-scored while others are positively scored. The total final score ranges from 17 (showing negative breastfeeding attitude) to 85 (indicating positive breastfeeding attitude). The original scale showed good reliability with Cronbach’s ranging from 0.68 to 0.86 and good validity [28]. In the current study, a Chinese version of the IIFAS is used and indicates moderate reliability with Cronbach’s α ranging from 0.589 to 0.685 and good validity with 0.996 [29].

Breastfeeding knowledge questionnaire (BKQ)

The BKQ is used to assess breastfeeding knowledge of maternal women. The questionnaire includes 18 items and was modified based on previous literature [30] by Ouyang et al. [31]. It is a closed-ended questionnaire with true or false responses and had good internal reliability with Cronbach’s α = 0.93 [31]. The common use in previous studies [31, 32] was calculating the percentages of true or false of each item. In this study, the researchers imply true as “1”and false as “0” and will then calculate the total score of the 18 items of each participant.

Breastfeeding self-efficacy Seale Short Form (BSES-SF)

Breastfeeding self-efficacy refers to the degree of confidence of mothers in their ability to breastfeed their infants. Breastfeeding Self-efficacy Scale (BSES) was developed by Dennis and Faux [33] in 1999 and was simplified in 2003 [34]. It was translated into Chinese by Liu et al. [35]. The Chinese version of the BSES-SF consists of 14 items with Cronbach’s α = 0.927. The scores’ range is 14 to 70 on a five-point Likert scale, with a score of 1 to 5 representing a range from “not at all” to “very confident”, with higher breastfeeding self-efficacy being associated with higher scores. The scale is divided into two dimensions: the skills dimension consists of nine items that measure the level of confidence in breastfeeding skills, and the personal internal reflection dimension of five items that measure attitudes and beliefs about breastfeeding.

Edinburgh postnatal depression scale (EPDS)

The EPDS is mainly used to assess the degree of postpartum depression. It was developed by Cox et al. [36], and translated into Chinese by Lee et al. [37] with a Cronbach’s α coefficient of 0.89, which showed good reliability and validity. In 2007, Guo et al. [38] translated and revised the scale according to the language habits of Chinese with a Cronbach’s α coefficient of 0.76 and the cut-off value of 9.5 [39]. It consists of 10 items, including mood, anxiety, fear, pleasure, self-blame, insomnia, coping ability, sadness, crying and self-harm. Each item has 4 points, and the total score is 30 points, with higher scores indicating more severe depression. In this study, postpartum depression was considered having a total score of ≥ 10 [40].

Social Support Rating Scale (SSRS)

The SSRS in a Chinses version was first developed by Xiao [41]. The scale included 10 items in three dimensions: objective support, subjective support and utilization of social support. The scores of items 1–4 and 8–10 are 1–4 points each. In item 5, the total score is scored with five options (A-E), ranging from “none “(1) to “full social support” (4). If the answer “none” in items 6 and 7 is scored for 0 points, and then the answer “other sources” is scored according to the number of sources. The scores of 35 and 45 are used as cut-off values to divide them into relatively low, general and relatively high social support. The Cronbach’s α coefficient ranged from 0.825 to 0.896, indicating good reliability of the scale [42].

Pregnancy-related anxiety questionnaire (PAQ)

The PAQ was developed by Chinese scholars Xiao Limin et al. [43] according to the characteristics of pregnant women in China, and is a self-assessment scale with 13 items using a 4-point scale ranging from 1 to 4. The Cronbach’s α coefficient and re-test reliability of the scale are 0.81 and 0.79, respectively. It focuses on three dimensions of worrying about the self (items 1–6), worrying about the health of the fetus (items 7–10, 13) and worrying about childbirth. The PAQ has no defined cut-off value while Zhang et al. [44] used the overall score of 75th percentile (P75) as the cut-off value for the presence or absence of pregnancy-related anxiety, i.e., 24 indicating the presence of pregnancy-related anxiety, otherwise it was none.

Postpartum specific anxiety scale-chinese version (PSAS-CN)

The Postpartum Specific Anxiety Scale (PSAS) was introduced in Turkey in 2016 by Assistant Professor Victoria Fallon [45]. The Chinese version was translated and revised by Xu et al. [46]. The scale consists of 50 items and contains four dimensions: (1) maternal competence and attachment anxiety; (2) infant health and safety; (3) infant care anxiety; and (4) mother’s psychosocial adjustment. The scale is a 4-point scale, with scores from 1 to 4 indicating “not at all,“ “occasionally,“ “often,“ " usually,“ and “always”. The higher the score, the more severe the symptoms of postpartum-specific anxiety. The scale has good reliability and according to Fallon et al. [45], and a score of 112 and above indicates a clinical level of anxiety. The Cronbach’s α coefficient for this scale is 0.95 [47].

Training and certification plans

Details of the data collection procedures are shown in Fig. 2. Collection will be completed by the same data collector, who will be trained on the study requirements, understanding of each questionnaire item, counseling for adherence and the eliciting of information from study participants in a uniform reproducible manner. The data collector will also be taught how to code each questionnaire item and how to enter data forms in the Excel spreadsheet. Each of the data collection forms and the nature of the required information will be discussed in detail on an item-by-item basis during a training session.

Participant withdrawal

Participants may withdraw from the study for any reason at any time. The investigator may also eliminate participants from the study in order to protect their safety and/or if they are unwilling or unable to comply with required study procedures after consultation with the researchers.

Data management

In the study, data will be entered electronically in an Excel file. Participant files will be stored in numerical order and stored in a secure and accessible place and manner. Participant files will be maintained in storage for a period of 3 years and uploaded to a web-based public database (ResMan research manager http://www.medresman.org.cn/pub/cn/proj/guide.aspx) upon completion of the study. The option to choose a value from a list of valid codes and a description of what each code means will be available where applicable.

Statistical analysis

Statistical analysis will be completed using SPSS (version 24.0). In order to compare the difference at baseline between the two groups, the two-sample t-test will be used for continuous variables and the χ2 test for classified data. Analyses of differences between two groups regarding maternal and neonatal morbidity outcomes, IIFAS, BKQ, BSES-SF, PAQ, PSAS-CN, EPDS and SSRS are evaluated in the same manner. In addition, one-way ANOVA analysis and two-sample t-test will be used to explore the influencing factors of the EBF rate. The data from the IIFAS, BKQ, BSES-SF, PAQ, PSAS-CN, EPDS and SSRS of the two groups at different time points (T0, T1, T2 and T3) will be tested using repeated measurement Analysis of Variance (ANOVA). For variables that have an interaction effect in repeated measurement ANOVA, a simple effect analysis will be carried out to further explore the effects of each factor. Cohen’s d will be reported to check the effect size. Cohen’s d will be used to evaluate the magnitude of difference between the two groups. According to the standard established by Cohen, the large, medium and small of the effect of d was divided into 0.8, 0.5, and 0.2 [48]. The randomized trial will use the statistical analysis “per protocol”. The significance level is set to less than 0.05 (double-tailed). P-values will be reported to four decimal places p-values and those less than 0.001 will be reported as p < 0.001.