Introduction

Infant mortality is one of the most critical indicators of a health system, significantly impacting the health and development of countries1. Out of 5.9 million children under the age of five who die each year globally, 2.7 million deaths occur during the neonatal period2. The global Sustainable Development Goals and the World Health Organization (WHO) aim to reduce neonatal mortality, recommending breastfeeding and the use of milk stored in milk banks as effective strategies to achieve this goal3.The WHO recommends exclusive breastfeeding for infants up to six months of age4, as breastfeeding improves gastrointestinal function, reduces acute respiratory infections, decreases mortality from diarrhea, enhances cognitive and physical growth, and lowers the risk of infectious diseases during infancy5. Worldwide, approximately 15 million preterm infants are born each year, who are at risk for respiratory diseases and necrotizing enterocolitis (NEC)6. Therefore, prioritizing breastfeeding in healthcare services is essential; however, when maternal milk is insufficient, donated breast milk from milk banks becomes a crucial nutritional source, especially for preterm and high-risk infants7. Insufficient milk supply in some mothers can be caused by various factors, such as physiological issues, hormonal imbalances, or anatomical challenges8,9,10. Feeding with donated breast milk from milk banks is an effective method for preventing infectious diseases, improving neurological and cognitive function, and reducing cases of Necrotizing Enterocolitis11.

Today, numerous human milk banks exist globally, particularly in low- and middle-income countries, facilitating the collection, processing, and distribution of donated breast milk. Human milk banks are non-profit organizations dedicated to providing pasteurized breast milk for vulnerable infants whose mothers cannot provide it through a donation process that includes screening, storage, and distribution according to existing regulations12. The first human milk bank was established in 1909 in Vienna, Austria, and today over 600 milk banks operate worldwide, with 200 located in Brazil5. In Iran, the first human milk bank was established in Tabriz around 2015, benefiting many premature and ill infants since its inception13. However, unlike other medical products derived from human sources, there are no minimum quality, safety, or ethical standards for donor human milk, nor is there a coordinating global body to inform national policies regarding milk banks14.

Despite the importance of donating breast milk to milk banks, especially for supporting premature and ill infants, there are barriers and limitations in this regard. These challenges largely stem from a lack of awareness about milk banking, religious and cultural beliefs, concerns regarding the safety of donated milk, misconceptions about milk banks, and the lengthy process involved in donating milk5. Therefore, if the health system aims to promote milk banks, it must invest in attracting milk donors. Educating mothers during pregnancy and breastfeeding, increasing awareness about the benefits of breast milk for premature infants, providing financial support, and fostering a positive attitude toward milk donation can significantly change breastfeeding mothers’ perceptions regarding donating milk to banks3,5,15. Among similar international studies, the research by Wambach et al. in 2019 aimed to describe the individual and social aspects of mothers donating breast milk to a bank in the Midwest United States. A sample of 50 human milk donors participated in this descriptive cross-sectional study. The results indicated that humanitarian motivations were among the reasons for donating milk to banks16. Findings from Smyk et al. in Polish country showed that out of all women participating in the study, 604 were aware of the existence of a human milk bank, most of whom learned about it through the internet. Among women with children (453), only 9 had donated breast milk. Reasons cited for not donating included insufficient extra milk, lack of knowledge about donation procedures, or unawareness of the existence of a bank15. The study by Golsanamloo et al.17 in Iran found that healthcare providers’ awareness and attitudes toward donating breast milk could have a moderate impact on donation rates. Additionally, research by Hosseinzadeh et al. in Iranian women indicated that factors such as education level, income, type of delivery, breastfeeding experience, and encouragement to donate could serve as predictors of knowledge; moreover, knowledge scores and encouragement were predictors of attitudes toward donation18. Attitude is one of the most significant factors influencing a mother’s willingness to donate breast milk19,20. Therefore, understanding the predictors of willingness to donate is crucial for effectively promoting this behavior7,21,22.

The desire to donate can be influenced by maternal behavior, and the Theory of Planned Behavior may provide insights into the decision to donate or not donate breast milk23,24. The Theory of Planned Behavior is a well-known behavioral change model25, which considers intention as the primary determinant of behavior. In this model, intention is influenced by three independent constructs: attitude, subjective norms, and perceived control26. An individual’s belief in the outcomes of their behavior and their evaluation leads to forming an attitude23,26. Regarding the effectiveness of the Theory of Planned Behavior on changing behaviors among pregnant women, studies by Fathi et al.27and Sharifi et al.28related to factors affecting exclusive breastfeeding based on this theory can be referenced. The results indicate that the Theory of Planned Behavior is recognized as one of the most important predictors for exclusive breastfeeding intentions. Investigating factors associated with willingness to donate breast milk to banks among pregnant women is crucial due to the significant impact breastfeeding has on both infant and maternal health. In Iran, despite efforts made, the rate of breast milk donation remains low; thus, a more detailed examination of factors influencing women’s decision-making is necessary. Therefore, this study aims to identify factors related to donating breast milk to banks among pregnant women based on the Theory of Planned Behavior.

Methodology

Study Design and setting

This descriptive and analytical cross-sectional study was conducted using stratified and convenience sampling methods on pregnant women attending women’s health and midwifery clinics affiliated with Mashhad University of Medical Sciences in 2024. Participants were required to be at least six months pregnant to be included in the study. Non-consent to continue participation and incomplete questionnaire responses were considered exclusion criteria.

Study participants and sampling

In the first stage of sampling, each midwifery clinic, including Imam Reza (AS), Qaem (AJ), Om al-Banin (SA), Shahid Hashemi Nejad, and Dr. Shariati hospitals, was considered a stratum. Subsequently, hospitals were sampled using convenience sampling proportional to their size. Using multiple linear regression as the primary analytical method, with a small to medium effect size (f²=0.07), a significance level of 0.05, a power of 0.9, and ten independent variables in the regression model, the sample size was determined to be 303 using G*Power 3.1.5 software. After accounting for a 10% dropout rate, the final sample size was set at 337 participants.

Data collection tool and technique

Data were collected using a researcher-made multi-part questionnaire completed in person by the participants. The first section included seven questions regarding demographic characteristics such as age, education level, occupation, pregnancy complications, previous delivery type, residence location, and awareness of milk bank activities. The second section contained twelve questions assessing knowledge and awareness about milk donation, scored using a three-level response format: yes, no, and I don’t know. The third section focused on constructs from the Theory of Planned Behavior. Items for each construct (attitude, subjective norms, perceived behavioral control, and behavioral intention) were adapted from relevant literature based on Ajzen et al.‘s guidelines25. Specifically, there were thirteen questions for attitude, seven for subjective norms, five for perceived behavioral control, and one for behavioral intention. Questions related to the Theory of Planned Behavior constructs were designed using a Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree), with total scores calculated out of 100.To ensure content validity, the questionnaire was reviewed by ten experts with at least three years of experience in human milk banking or health education faculty positions. Based on their feedback, adjustments were made to the questions; consequently, the Content Validity Ratio (CVR) was calculated at 0.71 and the Content Validity Index (CVI) at 0.85. Face validity was assessed through Impact Score evaluation among thirty individuals from the target population. Additionally, reliability was tested using test-retest consistency over two weeks with thirty participants from the target population. The reliability coefficients for knowledge, attitude, perceived behavioral control, subjective norms, and behavioral intention were found to be 0.95, 0.93, 0.97, 0.95, and 0.96 respectively; overall reliability for the questionnaire was determined to be 0.95. To collect data, researchers explained the study’s purpose to participants upon entering the research environment and provided them with the questionnaire after obtaining informed consent.

Data Analysis

Initially, data were described using central tendency and dispersion indices. To examine relationships between constructs of the Theory of Planned Behavior and other independent quantitative variables concerning mothers’ willingness to donate milk at clinics affiliated with Mashhad University of Medical Sciences, Pearson correlation coefficients were utilized due to non-normal data distribution. For comparing distributions of willingness scores across binary variables, the Mann-Whitney U test was employed; for categorical variables with more than two levels, the Kruskal-Wallis test was used. To assess relationships between constructs of the Theory of Planned Behavior while controlling for other demographic or independent variables concerning mothers’ willingness to donate milk, multiple linear regression models were applied. All statistical tests and models were executed using SPSS version 26 at a significance level of 0.05.

Results

Demographic characteristics of participants

The average age of participants in this study was 30.16 years. Only 19.7% (65 individuals) of the participants were aware of milk bank activities prior to the study, with staff being their primary source of information. Among the participants, 43% (143 individuals) held a university degree, and the majority, 74.5% (246 individuals), were homemakers. Other results are presented in Table 1. The Mann-Whitney U test results indicated a significant relationship between the independent variables of residence location and awareness of human milk bank activities with the dependent variable of willingness to donate milk. Urban residents showed a greater willingness to donate milk compared to rural residents (p = 0.031), and individuals who were aware of milk bank activities expressed a higher willingness to donate milk than those who were unaware (p = 0.003).The Kruskal-Wallis test results showed no statistically significant relationship between the variables of education level, type of occupation, number of pregnancies, and previous delivery type with the dependent variable of donating milk to the bank (p > 0.05). (Table 1)

Table 1 Demographic variables of female participants in the study and relationship with willingness to donate milk.
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According to the research findings, the mean and standard deviation scores for awareness regarding milk donation were 35.47 ± 22.65, for attitude 67.86 ± 10.1, for perceived behavioral control 60.75 ± 13.85, for subjective norms 67.41 ± 11.8, and for willingness to donate milk 70.54 ± 20.33 (Table 2).

Table 2 Mean scores of the constructs of the theory of planned behavior regarding willingness to donate milk among women participating in the study.
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Based on the results of this study, age (r = 0.118), awareness (r = 0.413), attitude (r = 0.562), perceived behavioral control (r = 0.542), and subjective norms (r = 0.521) had a significant positive correlation with the willingness to donate milk among participating women (p < 0.05). Additionally, Spearman’s test results indicated that awareness was significantly and directly related to attitude (r = 0.575), perceived behavioral control (r = 0.555), and subjective norms (r = 0.503). Regarding the attitude variable, there was also a significant direct relationship between perceived behavioral control and subjective norms (Table 3).

Table 3 Correlation between constructs of the theory of planned behavior and willingness to donate milk among participating women.
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In this section, variables that had a p-value of less than 0.10 in the univariate analysis were included in the multiple linear regression model to simultaneously assess the relationship of these variables with the willingness to donate milk to the human milk bank. According to the results of the multiple linear regression test, the final model was able to explain 40% of the variance in willingness to donate milk among women. The findings from the multiple regression model indicated a significant direct relationship between attitude, perceived behavioral control, and subjective norms of pregnant women with their willingness to donate milk. Specifically, for each one-point increase in attitude, perceived behavioral control, and subjective norms, the willingness to donate milk increased by 0.711, 0.243, and 0.408 points, respectively (Table 4).

Table 4 Results of multiple Linear regression model for simultaneous examination of independent variables with willingness to donate milk to the human milk bank.
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Discussion

The present study was conducted to determine the factors associated with breast milk donation to milk banks among pregnant women based on the Theory of Planned Behavior. Overall, the results of this study showed that the level of willingness of pregnant women to donate breast milk was relatively good. This level of suitability could be due to the positive attitude of Iranian pregnant women towards breast milk donation, as the results of the study also indicated a suitable level of attitude among the participating pregnant women. In line with these results, Mary Gorreth Namuddu in her study conducted on pregnant women in Nigeria showed that exposure to human milk banking activities and breastfeeding counseling during prenatal care, which are factors related to attitude, increases the willingness to donate breast milk among women29. The results of this study showed that pregnant women living in urban areas had a greater willingness to donate breast milk compared to women living in rural areas. This trend can be attributed to several factors, including socio-economic conditions, access to healthcare, and cultural attitudes towards breastfeeding and breast milk donation. Urban areas often have higher household incomes and better access to education, which can influence health behaviors, including breast milk donation30. Additionally, women in urban areas usually have better access to healthcare services, including maternal and child health programs that promote breastfeeding and breast milk donation31.

Based on the results of this study, age had a positive and significant correlation with the willingness to donate breast milk among the participating women, and women who were older had a greater willingness to donate breast milk. This can be attributed to factors such as the greater experience of older women, better understanding of social support, and higher altruistic motivations among older women. Older women often have more life experience, which can strengthen feelings of empathy and altruism32. Additionally, older women may have stronger social networks, including family and friends who support the idea of breast milk donation33. Mohammed A. M. Ahmed also showed in a study conducted on 410 mothers postpartum that the willingness to donate breast milk is influenced by factors such as age, and older mothers show more willingness to donate breast milk due to their understanding of the benefits of breast milk donation for infants34.

Based on the results of this study, awareness had a positive and significant correlation with the willingness to donate breast milk among the participating women. Specifically, as the awareness of pregnant women about the benefits of breast milk and milk banks increased, their willingness to donate also increased. Awareness plays a fundamental role in shaping attitudes towards breast milk donation and thereby increases the willingness to donate breast milk among pregnant women35. A study in southeastern Nigeria in 2018 also showed that awareness about breast milk donation is a significant predictor of women’s willingness to donate and receive breast milk36. Regarding attitude, the results of this study showed that attitude had a positive and significant correlation with the willingness to donate breast milk among the participating women. Specifically, pregnant women who had a better attitude towards breast milk donation had a greater willingness to donate breast milk. The relationship between attitude and willingness to donate breast milk is multifaceted, and factors such as altruism, knowledge, the influence of healthcare providers, cultural beliefs, and personal experiences play vital roles in this area17. Na Zhang and colleagues also showed in their study conducted on postpartum women that having a positive attitude towards breast milk donation is one of the effective factors in breast milk donation37.

Based on the results of this study, perceived behavioral control had a positive and significant correlation with the willingness to donate breast milk among the participating women. Specifically, pregnant women who had better perceived behavioral control had a greater willingness to donate breast milk. Perceived behavioral control refers to an individual’s perception of the ease or difficulty of performing a behavior. These findings indicate that when women feel they have the ability and necessary resources to donate breast milk, they have a greater willingness to do so38. In a study conducted by Shirin Shahbazi Sighaldeh on breastfeeding women in Iran, it was shown that perceived behavioral control as an important variable can improve the intention of breastfeeding mothers to donate breast milk39. The results of the study regarding subjective norms showed that subjective norms had a positive and significant correlation with the willingness to donate breast milk among the participating women, and women who had a better status in terms of the subjective norms variable had a better willingness to donate breast milk. Subjective norms refer to an individual’s perception of social expectations for adopting a specific behavior40. These findings indicate that when women perceive social support from important sources such as family and friends for breast milk donation, they have a greater willingness to perform this action39. Wambach and colleagues also showed in their study that women who feel supported in various ways by their husbands, families, and friends have a greater willingness to donate breast milk16.

Limitations

This study had strengths and limitations. This research was conducted with a suitable sample of pregnant women and used valid and reliable tools, and the questionnaires were completed in person and through interviews, which can minimize measurement bias for the variables of this study. Given the cross-sectional nature of this study, one of its weaknesses was that only relationships between variables could be measured. Additionally, the challenge of fully generalizing the results to other communities and cultures is an additional limitation of this research.

Conclusion

The Theory of Planned Behavior is a suitable predictor for the willingness to donate breast milk among pregnant women, and the constructs of this model, including attitude, perceived behavioral control, and subjective norms, have a positive correlation with the intention and willingness to donate breast milk. Therefore, attention to these factors is essential for the establishment and expansion of milk banks. Additionally, based on the results of this study, integrating activities related to breast milk donation and reception into prenatal care and education programs promoting breastfeeding can increase the acceptability and use of milk banks. Furthermore, to promote breast milk donation, tailoring breast milk donation programs based on the effective factors identified in this study can help increase the overall rate of donation and support infants in need.