Sustainable Breastfeeding: A State-of-the Art Review

Abstract

Background:

Disparities in breastfeeding rates and exclusivity exist across regions and countries despite multifaceted breastfeeding promotion efforts in recent decades. Markets for artificial milk formula continue to grow as its substitution for breastfeeding is common. A new approach is needed for breastfeeding promotion strategies.

Research Aim:

This state-of-the-art review aimed to describe the implications of not-breastfeeding on the environment within the context of food system sustainability.

Method:

A total of 19 peer-reviewed articles within a 20-year timeframe were included in this review. Authors searched five databases for articles including Science Direct, GreenFILE, Springer Link, ProQuest, and PubMed.

Results:

The demand for artificial milk formula production as a replacement for breastfeeding results in increased greenhouse gas emissions, water pollution, and waste, thereby aggravating problems with freshwater scarcity. A short duration of breastfeeding and limited exclusivity have been associated with close birth spacing and contributing to global population growth. Breastfeeding is a healthy, sustainable diet, and a culturally acceptable first food. It advances health equity and food security. Exclusive breastfeeding for the first 6 months of life can be promoted with emphasis on total carbon footprint reduction, prevention of waterway degradation, and natural birth spacing, thereby sustaining food systems at large.

Conclusion:

It is important to reform food, nutrition, and environmental policies to protect exclusive breastfeeding while decarbonizing artificial milk formula production. More research is needed to provide directions for new breastfeeding promotion strategies connecting breastfeeding with environmental stewardship.

Keywords

breastfeeding breastfeeding practices breastfeeding support Global Strategy for Infant and Young Child Feeding sustainability

Key Messages

Globally, substitution of artificial milk formula for breastfeeding continues to affect breastfeeding rates with disparities across regions.

Artificial milk formula production increases the total carbon footprint and waterway degradation. Short breastfeeding duration and limited exclusivity is associated with global population growth.

A policy-driven culture shift toward exclusive breastfeeding for the first 6 months will help to sustain the global food system.

Findings warrant more research toward educating lactation counselors and healthcare providers on the relationship between breastfeeding with environmental stewardship.

Background

Infant feeding practices have evolved over time to include breastfeeding with mother’s own milk, wet nursing, bottle feeding, and artificial milk formula use (Davidove & Dorsey, 2019). The advancement of formula manufacturing and the industry’s aggressive advertisement of artificial milk formula directly to the public negatively influences breastfeeding practices. A global decline in breastfeeding is thought to be attributable to aggressive marketing of artificial milk formula to developing countries (Lozada-Tequeanes et al., 2020). The marketing strategy used to promote artificial milk formula has driven its over-consumption, discouraged breastfeeding, and undermined confidence in breastfeeding (Davidove & Dorsey, 2019; Hernández-Cordero, et al., 2019; Lozada-Tequeanes et al., 2020). Environmental costs are not fully accounted for in the market price of formula, nor fully understood by consumers. This has aided the growth of artificial milk formula consumption (Smith, 2019). Despite the multifaceted efforts to improve breastfeeding rates over the past decades, exclusive breastfeeding rates for infants under 6 months increased only marginally while artificial milk formula sales have nearly doubled (Clark & Ghebreyesus, 2022). A new approach is needed to promote breastfeeding.

The replacement of breastfeeding with artificial milk formula is still not uncommon and disparities exist in breastfeeding rates across regions, within and between countries (Centers for Disease Control and Prevention [CDC], 2020). As one example, in the United States, while 84.1% of women have tried breastfeeding at some point, only 25.6% of them maintain exclusivity at the end of the first 6 months (CDC, 2020). Globally, 44% of newborns are put to the breast within the 1st hour after birth and 95% of infants have ever been breastfed, yet only 40% of children under 6 months are exclusively breastfed (Arts et al., 2018). The health benefits of breastfeeding are widely known, including protection against the risk of childhood infections and minimizing nutrition-related harm to cognitive development in early childhood (Holla-Bhar et al., 2015; Victora et al., 2016). Early termination of breastfeeding hinders natural birth spacing (Pimentel et al., 2020) and increases the fertility rate, which has contributed to growth in global population (Becker et al., 2003; Berens & Labbok, 2015; Stevens et al., 2009). Population growth is predicted to exceed 9 billion by the mid-21^st century and is a threat to global food availability.

The costs of not-breastfeeding extend to environmental and economic loss. Although breastfeeding at the breast is not a zero-greenhouse gas emission activity due to emissions generated by the breastfeeding parent’s diet (Amonker et al., 2019), the replacement of breastfeeding with artificial milk formula generates a carbon footprint nearly twice that of breastfeeding. Exclusive formula feeding for 4 months has an environmental cost 35%–72% greater than exclusive breastfeeding for the same period (Andresen et al., 2022). Emissions from artificial milk formula production and waste generated by ancillary materials that are needed for formula use influence climate change. In addition, a large demand for formula feeding will divert energy and freshwater to livestock for formula production (Davidove & Dorsey, 2019). The global economic loss of not breastfeeding is estimated to be US$341.3 billion annually (Walters et al., 2019).

The promotion, protection, and support of breastfeeding are exceptionally cost-effective strategies for improving child survival and reducing the burden of childhood disease, as well as balancing global food systems. It is time to view breastfeeding as a healthy sustainable diet and to examine the impact of not breastfeeding on health, nutrition, and the environment in the context of food systems sustainability.

A state-of-the-art (SotA) review provides an opportunity to assess the literature using a time-based overview of the published evidence (Barry et al., 2022). SotA reviews are a new approach to literature reviews that address current topics and can offer a new perspective highlighting an area in need of further research. Using this design, we aim to explain how important it is to understand breastfeeding in the context of global food system sustainability, and suggest next steps. We examine the implications of using artificial milk formula to replace breastfeeding on the environment within the context of global food system sustainability.

Method

Design

This is a state-of-the art review that aimed for a comprehensive search of current literature to summarize the state of knowledge regarding the relationship between breastfeeding and the environment we live in (Barry et al., 2022; Grant & Booth, 2009).

Sample

To investigate the harmful risk of not breastfeeding on the environment, studies that explored the link between artificial milk formula/breastmilk substitute feeding and water usage, carbon footprint, birth spacing, or environmental impact were searched. Inclusion and exclusion criteria of studies in this review are presented in Table 1. Part of the purpose of this type of review is to identify how and when studies were completed; therefore, papers including commentaries, research articles, and grey literature were encouraged (Barry et al., 2022). This review included commentaries, primary research, meta- and systematic-review articles, and grey literature for a total of 19 articles. (Figure 1)

Table 1.

Screening Criteria.

Inclusion	Exclusion
• Studies published in English, Jan 2001-June 2022, in peer-reviewed journals • Primary studies • Commentaries • Reviews: Systematic and Meta Analyses	• Studies published in language other than English or in dissertations • Unrelated to breastfeeding

Figure 1.

PRISMA Flow Chart of Study Selection (Page et al., 2021).

Data Collection

We searched the literature for peer-reviewed articles that were published within a 20-year timeframe (2001–2022). We additionally included commentaries and reviews in the search as well as primary research articles. We searched five databases: Science Direct, GreenFILE, Springer Link, ProQuest, and PubMed. No articles were identified from Cochrane Database of Systematic Reviews. Search statements were composed of a combination of keywords as follows: [Formula Feeding AND Carbon Footprint], [Breast Milk Substitutes AND Carbon Footprint], [Formula Feeding AND Water Usage], [Breast Milk Substitutes AND Water Usage], [Formula Feeding AND Environmental Impact], [Breast Milk Substitutes AND Environmental Impact], [Birth Spacing AND Environmental Impact], [Birth Spacing AND Carbon Footprint], [Inter-pregnancy interval AND Carbon Footprint], and [Inter-pregnancy interval AND Environmental Impact]. Additional articles were derived from a manual search of the cited references in the articles included in this review.

Two reviewers independently searched the database using the same search statements. Duplicate articles were removed from the initial collection of the search. Articles were screened by reviewing the title and abstract for relevance to this review topic. Then, the full text of the articles were screened. After full text screening, the two reviewers met to reach consensus on which articles should be included in the narratives. A total of 19 articles were analyzed.

Measurement and Data Analysis

Given the variations of the articles reviewed, the data were summarized by article themes and findings. Article themes ranged from article focus to study aims and methods. The findings of each article were synthesized and organized into three themes for this review: Breastfeeding and carbon footprint reduction; breastfeeding and water usage reduction; and breastfeeding and natural birth interval (see Table 2).

Table 2.

Summary of Studies Reviewed on Breastfeeding and Environmental Stewardship.

Author, Year Country	Article Type Study Method	Area of Theme	Findings/Author Conclusions
Davidove and Dorsey (2019) USA	Commentary Narrative BF as sustainable food system: To propose a separate sustainable development goal on BF providing a necessary framework for corrective action To provide sufficient evidence to promote this behavior as a universal element of healthy sustainable diets To describe the social, economic, and environmental costs of using infant formula to replace BF from both global and US perspectives	Carbon footprint reduction Water usage reduction	BF was the most sustainable method of infant feeding. Breast milk had near-zero carbon footprint. Only an additional 500 calories and one liter of water per day were needed for lactation. BF for the first 6 months could conserve 105,280 liters of water and 488 kg CO2e. The environmental cost of using AMF: water and carbon footprint generation, deforestation of land, and the loss of biodiversity required for growing cattle feed and oil palms. It is important to utilize existing programs in schools and peer counseling programs, support groups, and parenting resources to reach a vast audience with information on BF and environment, embedding value of stewardship at every age. Publication of literature recognizing BF as the universal foundation of a healthy sustainable diet for women, infants, and children is a first and vital step.
Becker and Ryan-Fogarty (2019) Ireland	Letter Narrative Auxiliary equipment used for infant feeding and its effect on environment.	Carbon footprint reduction	Variations in materials used for single use bottles, teats, and packaging created difficulties in appropriate waste management. Direct BF was healthier and more environmentally sustainable compared to using pumped breast milk. Electric breast pumps were associated with waste plastic, waste electronics, and energy demand. Reduced use of AMFs and associated waste management should be considered at individual, hospital, and national policy level.
Cadwell et al. (2020) Canada, Mexico, and the United States.	Original Research GHG analysis: To compute a minimal estimate of GHG emissions for powdered MF products sold in North America comprising Canada, Mexico, and the United States. Methods: Retrieved industry data on powdered AMF and the recipes for AMF blends. Used available published literature to calculate emission contribution of each ingredient according to the percentage of its inclusion. Computed carbon footprint of each type of powdered AMF and translated measurements of carbon dioxides using GHG equivalencies.	Carbon footprint reduction	Estimated emissions: 8.49 kg CO₂e /kg skimmed milk powder;10.02 kg CO₂e /kg whole milk powder; 9.56 kg CO₂e /kg growing up powder; 5.38 kg CO₂e/kg special powder. In 2016, 59.06 kg CO₂e per capita (0-3 years old) in North America with each country’s variations. Highest emissions were from more use of follow-on and growing up powdered AMF. In 2016, the annual total emission was 1,161,932 tons of CO₂e.
Joffe et al. (2019) UK	Editorial Narrative Environmental cost of decades of disinvestment in BF service support To highlight environmental cost of AMF’s contribution to environmental degradation and climate change	Carbon footprint reduction	Most AMF are based on powdered cows’ milk. Water footprint of milk powder is approximately 4700L/kg. Additives to AMF magnify negative environmental impact, e.g., palm, coconut, rapeseed, and sunflower oils. Approximately 3.8 tons of AMF is produced annually by only 40-50 AMF processing plants worldwide. BF for 6 months saves an estimated 95-153 kg CO₂e per infant compared to exclusive AMF feeding. Half of these GHG come from follow-up AMF, which is known to be unnecessary and harmful. Societal responsibilities include: medical education to support BF women, and improve information and care, enable parents to develop feeding plans as well as birth plans; better access to screened donor milk from a regulated milk bank when supplementation is needed; lactation support providers; cultural change to encourage and support BF.
Long et al. (2021) Ireland and China are used for the case study.	Original Research Case study Proposing an analysis framework to incorporate infant feeding into large scale energy system models To move beyond emissions and consider the social justice elements of an energy transition. To demonstrate that the emissions saved from decarbonizing AMFs production have an opportunity cost. To discuss the decarbonization of AMF in relation to the principle of justice and non-maleficence. To argue that BF support can be considered a demand side measure for mitigating climate change	Carbon footprint reduction	The emission savings achieved from the minimum 50% exclusive BF target is greater than decarbonizing current consumption with renewable gas alone. The harms associated with AMF use can be exacerbated if greater social license is granted to its use via decarbonized production which could bring potential overconsumption. The social harms associated with AMFs include the costs to mothers of removing maternal identity, lessening chances for bonding and experiencing normal bodily function. BF support to meet WHO nutrition target of 50% exclusive BF rates is a demand-side measure in the energy transition. The emission analysis demonstrated that the greatest savings can be achieved through a combined effort of meeting the WHO minimum nutrition target and decarbonizing AMFs. Although fuel-substitution with renewable gas appears to be a solution for decarbonization, it does not align with social long-term value.
Smith (2019) Austria	Commentary Narrative Mass AMF production and its consequences. Carbon footprint added by AMF use accelerates environmental harms. Policy implications related to increased AMF use.	Carbon footprint reduction Water usage reduction	Per 1 kg of AMF production, 11-14 kg of CO₂e of GHG are added to the planet by the time it is fed to infants. Feeding an infant exclusively with AMF for 6 months adds 200 kg CO₂e of GHG to the planet, equivalent of 18 billion miles of car travel. Individuals may have far less control of infant feeding choice because of the life-pressure of returning to work and AMF marketing appeal. Well-established effective policies and interventions for improving BF are necessary to protect BF, e.g., paid maternity leave, Baby-Friendly Hospital Initiative, WHO International Code implementation. Promoting dietary change to BF and plant-based diet could improve nutrition and health as well as reduce GHG emissions.
Amonkar et al. (2019) USA	Original Research To analyze the cradle-to-grave GHG emissions impacts of breast milk production, pumping, refrigeration/re-heating, and bottle feeding vs. AMF production, preparation, and bottle feeding. Method: Life cycle inventory analysis and respective GHG emissions were determined along the 8 life cycle stages: packaging materials, AMF ingredients (or mother’s diet), inbound transportation, retailing, use phase, end of life.	Carbon footprint reduction	When women relied on supportive equipment (i.e., breast pumps, bottles, refrigerators, freezers, and reheating equipment) to breastfeed exclusively, breast milk feeding resulted in greater GHG emissions (1,463-2,202 g CO2e/day per infant) than AMF feeding. (873-1,400 g CO₂e/day), reflecting standard maternal lifestyles. Evidence suggested that breastfeeding women who avoided using pumps and bottles may generate lower emissions than women who opted for AMF feeding.
Andresen et al. (2022) Norway	Original Research To differentiate the ecological implications of 4 months exclusively using AMF in contrast to exclusive BF over the same duration. Method: Evaluated the ecological effect of producing and distributing powdered AMF; assessed the environmental consequences of making AMF ready to drink (including bottle production and preparation); estimate the environmental impact of BF; summed the overall environmental impact for a 4-month feeding period.	Carbon footprint reduction	BF was more eco-friendly than using AMF. In all categories, for every 1 kg of ready-to-consumed AMF, the impact was higher than breast milk, ranging from 24-60% AMF feeding exclusively for four months had an environmental cost 35-72% greater than exclusively BF for the same period The carbon footprint of AMF feeding was nearly twice that of BF. Mother's diet also influenced the environmental footprint of BF. E.g., an increased intake of calories sourced from animals impacts around 3 to 5 times more if the mother consumed a vegan diet.
Pope et al. (2021) Australia	Review Method: Database search of peer-reviewed literature on environmental impact of AMF and dairy industry	Carbon footprint reduction Water usage	AMF carbon footprint was double that of BF; 1 kg of AMF consumed 699L of blue water. GHG emissions from livestock accounted for 57% agricultural emissions. 1.5kg CO₂e per kg of energy-adjusted milk production 6280L rainwater required for 1 kg of AMF production. 524L grey water consumed for 1 kg of AMF production AMF market price did not reflect AMF environmental consequences.
Karlsson et al. (2019) Sweden	Original Research To estimate the GHG emissions or carbon footprint, from production and consumption of AMF. To compare carbon footprint from using powdered AMF vs. from BF Method: Carbon footprint for production of AMF accounted for AMF recipe ingredients (e.g., raw milk, vegetable oil), powder processing (e.g., energy needed for water removal, pasteurization, cooling), plus packaging and transport. Countries of data: New Zealand, USA, Brazil and France. Carbon footprint for consumption accounted for transportation of AMF from plan to retail, baby bottle manufacture, in-home sterilization, and AMF feeding preparation. Countries of data: UK, China, Brazil, and Vietnam	Carbon footprint reduction Water usage reduction	Climate impact of feeding AMF for 6 months = 226-288 kg CO₂e Average carbon footprint per 1 kg of AMF production = 7.1- 11 kg CO₂e Average carbon footprint per 1 kg of AMF consumption = 11-14 kg CO₂e Climate impact of BF for 6 months = 123-162 kg CO₂e Average carbon footprint for required extra food to breastfeed = 5.9-7.8 kg CO₂e Net benefit of BF = 95-153 CO₂e One should consider the functional difference between BF and use of AMF because AMFs are a necessity for medical or other reasons while BF has positive health and developmental outcomes.
Moglia et al. (2018) US, the UK, Australia, Spain	Review Narrative To review what influences people’s decision to conserve water, what influences whether people persist with water conservation behavior and what contributes to awareness and familiarity of water conservation behaviors. Methods: Keyword search literature review using Scopus abstract and citation database	Water usage reduction	Water security is influenced by population growth, competition with other demands, droughts, over-extraction, and pollution of fresh water sources. Water conservation behaviors were encouraged by regular media attention around drought, providing procedural information about how to reduce water demand. Drought events coupled with increasing water demand driven by population growth needs to be recognized. Effective water-conservation strategies focus on policies that create a culture shift on how individuals perceive water usage reduction
Molitoris et al. (2019) 77 countries	Original Research To investigate how the relationship between preceding birth intervals and infant mortality varies across developmental contexts while applying uniform methods that can minimize residual confounding from unobserved heterogeneity. Methods: Used a sample of 4.5 million births from 77 countries at various levels of development. The effects of birth spacing on infant mortality were analyzed using a linear probability model	Natural birth interval	Birth intervals shorter than 36 months substantially increase the probability of infant death. The degree of importance of birth intervals on infant mortality was inversely varied by maternal education and the strength of relationship varied regionally. The birth intervals are important for perinatal outcomes in low-income countries but are much less consequential in high-income settings.
Rosenberg et al. (2021) Israel	Original Research To examine the influence of tandem BF on the macronutrient content of human milk Methods: Human milk samples from tandem BF participants (n=18) were compared to samples from non-tandem BF participants (n=31). Samples were collected during the last month of pregnancy, 72 hours postpartum (colostrum), and 14-60 days postpartum (mature milk). Macronutrients were measured by mid-infrared spectroscopy.	Natural birth interval	Colostrum and mature milk of tandem BF and non-tandem BF participants were similar. The only difference was the carbohydrate content, which was higher in tandem BF participant milk
Sinkiewicz-Darol et al. (2021) Poland	Original research To provide descriptive statistics about tandem BF mothers To describe the composition of human milk in cases of women that were breastfeeding in tandem and after weaning a toddler. Methods: Breast milk from tandem BF women and after weaning were examined. Macronutrient analysis–total fat, crude protein, true protein, carbohydrates, dry matter, and energy value.	Natural birth interval	Tandem BF women in the study (n = 13, mean age = 31.6 years, SD = 4), older child (mean age = 34 months, SD = 8), younger child (mean age = 6.6 months, SD = 5.1) The duration of lactation influences milk composition. Higher fat content, energy value and total protein concentration were found in tandem BF milk during tandem BF compared to the milk after weaning the older child. Carbohydrate content was the same during and after weaning. Breast milk composition evolved as the duration of lactation increases, which was dictated by the changing needs of children. BF more than one year and feeding two children in tandem did not adversely affect the quality of breast milk.
Damtie et al. (2021) Ethiopia	Meta-analysis Review To determine the association between short birth spacing and contraceptive use, BF duration, and educational status among reproductive-age women in Ethiopia Methods: A meta-analysis with 9 articles was performed using a random-effect model. The pooled prevalence of short birth spacing and log odds were estimated to determine associations	Natural birth interval	Women who had never used contraception before conception of the last child were 3.87 times more likely to have short birth spacing. The odds of practicing short birth spacing was 16.9 higher among women who breastfeed their child less than 24 months as compared to those who breastfeed 24 months and more. OR=16.9, 95% CI: [2.69, 106.47] Babies delivered from those women who practice short birth spacing might experience low birth weight, small size for gestational ages, preterm birth, and congenital anomalies.
Becker and Ryan-Fogarty (2016)	Brief Report Narrative To discuss environmental effect of reliance on pumped mother’s milk for feeding	Carbon footprint reduction	Economic and environmental costs were involved in the equipment purchased relating to pumping, storing, and feeding. Electricity needs, battery, many single use or single-user items resulted in waste and health inequality. An association found with obesity risk and bottle feeding of mother’s own milk. Research is needed for the relationship between exclusive pumping and lactational amenorrhea. Backcasting methodology is needed to envision future sustainability goals and strategize infant feedings
Ryan-Fogarty et al. (2017) Ireland	Original Research To mitigate ready-to-use AMF waste in Irish Maternity Service by (1) identifying sources of waste ready to use AMF, (2) quantifying ready to use AMF procured and volumes of liquid waste, and (3) evaluating the solutions to prevent and mitigate this waste. Methods: Using backcasting methods, authors developed normative scenarios for AMF food waste management	Carbon footprint reduction	Improve infant diet with exclusive BF and decrease waste. Waste milk and AMFs had high biological oxygen demand, were sources of nitrogen and phosphorus pollution and may cause operational issues to on-site wastewater treatment plants where dilution factors may be lower. Waste prevention and reduction should be practiced. Solutions included: increase exclusive BF rates; increase use of human donor milk and reduce AMFs supplementation; wider range of bottle sizes; reuse, recycling, and other recovery; potential recovery as animal feed; onsite composting or anaerobic digestion; off-site composting or anaerobic digestion. The most viable, and ultimately desirable opportunities for the treatment of AMF food waste were its prevention of use at source.
Dadhich et al. (2021) Australia	Original Research To describe exploratory estimates of GHG emission factors for all infant and young child milk AMF products To estimate national GHG emission association with AMF sold in selected countries in the Asia Pacific region Methods: Secondary data analysis descriptive design incorporating a Life Cycle Assessment concept and methodology. Data were from both importing and exporting formula country reports: India, Philippines, China, Malaysia, Australia, and South Korea	Carbon footprint reduction	Estimated average GHG emissions were as follows: (1) 3.95 kg CO₂e per 1 kg for AMF targeting 0-6 months infants, (2) 4.04 CO2e per 1 kg for AMF targeting 7–36-month children, (3) GHG emissions were highest in China. Aggregated GHG emissions due to AMF in all 6 countries were as follows: 1.2 million tons CO₂e from AMF for infants; 3.7 million tons CO₂e from follow up AMF. Follow up AMF production sales were the most important GHG emission sources in all countries except for Australia. Results were concerning for interacting influences by large population size, declining BF rates, and rising affluence in countries of the region. Stronger and more comprehensive national measures to regulate the marketing of commercial food products for infants and young children as recommended by WHO were recommended. BF is affordable, culturally acceptable first food, and advances social, health equity and food security.

Note. BF = Breastfeeding; AMF = Artificial Milk Formula; CO₂^e = Carbon Dioxide Equivalents; GHG = Greenhouse Gas. Infant milk formula = AMF which has been standardized throughout this paper. Various terms were used for AMF across different studies.

Peer-reviewed journal articles in both online and paper publication formats were included. Findings of the review are presented in narratives with one summary table. Based on the type of current review, no formal quality assessment of the reviewed articles was conducted (Grant & Booth, 2009).

Results

Breastfeeding and Carbon Footprint Reduction

The Earth’s surface cools down at night by releasing the sun’s heat absorbed during the day into the air. This process is interrupted and slowed down if the heat is trapped in the Earth’s atmosphere by greenhouse gasses, leading to global warming (United States Environmental Protection Agency [U.S. EPA], 2015a). The greenhouse gasses are natural and man-made gasses that include carbon dioxide, methane, nitrous oxide, and fluorinated gasses (U.S. EPA, 2015b). Of the total greenhouse gas emissions, carbon dioxide is mostly emitted by human activities, for example, transportation (27%), electricity production (25%), industry (24%), commercial and residential (13%), agriculture (11%), and land use and forestry (13% of 2020 greenhouse gas emissions; U.S. EPA, 2015b). Food production and processing alone accounts for 25% of carbon dioxide emissions (Cadwell et al., 2020). The amount of carbon dioxide in the atmosphere has increased more than 20% in 40 years, from annual average 339 parts per million in 1980 to 412 parts per million in 2020, largely due to human activities. This amount represents well over 50% of the total increase in atmospheric carbon dioxide since the industrial revolution (Cadwell et al., 2020). Over the past decade, increases in carbon dioxide are responsible for about 82% of the increase in the heat-trapping capacity of the atmosphere.

The emissions of greenhouse gasses other than carbon dioxides are expressed as carbon dioxide equivalents, which are the product of the given gas mass multiplied by the gas’ global warming potential. The global warming potential allows comparisons of global warming impacts of different gasses. It is a measure of how much energy the emissions of 1 ton of a gas will absorb over a given period of time (i.e., 100 years), relative to the emission of carbon dioxide (U.S. EPA, 2015a, 2015b). For example, when the global warming potential of methane is 28, it means that the emission of methane is equivalent to emissions of 28 carbon dioxide. The total greenhouse gas emissions, both carbon dioxide and carbon dioxide equivalents, generated by human activities are described with carbon footprints (Durojaye et al., 2020). Carbon dioxide equivalents are the standard unit of a carbon footprint measure because a single number of carbon dioxide equivalents allows for easy comparisons between carbon footprints consisting of various amounts of greenhouse gasses.

Breastfeeding lowers the total carbon footprint through reduced land and water resource use compared to what is needed for the production and consumption of artificial milk formulas. Breastfeeding women require an additional 500 calories and 1 L of water per day to sustain breastfeeding for a day, whereas 21.8 kg carbon dioxide equivalents of greenhouse gasses and 4700 L of water are needed per 1 kg of artificial milk formula powder generated (Davidove & Dorsey, 2019). Breastfeeding for 6 months conserves approximately 488 kg carbon dioxide equivalents of greenhouse gasses and 105,280 L of water (Davidove & Dorsey, 2019). Breastfeeding can have 95–153 kg carbon dioxide equivalent reduction in carbon footprint per infant compared to exclusive artificial milk formula feeding, equal to the removal of 50–77.5 thousand cars off the roads per year (Joffe et al., 2019). Further reduction of the total carbon footprint can be made if breastfeeding women consume a plant-based diet following dietary guidelines, because greenhouse gas emissions from animal-based food production is nearly twice that of plant-based food production (Xu et al., 2021).

Long et al. (2021) suggested an innovative solution to reduce emissions in the production of artificial milk formula. Manufacturers that produce artificial milk formula could be targeted in efforts to change to renewable gas to decarbonize their process of formula production. However, the emission savings for achieving a minimum 50% exclusive breastfeeding target are greater than decarbonizing the current consumption with renewable gas alone (Long et al., 2021). Given that artificial milk formula serves a functional purpose for reasons including medical use, increasing exclusive breastfeeding for 6 months duration should be accompanied by this renewable gas solution to have a meaningful positive influence on the environment (Long et al., 2021).

Breastfeeding and Water Usage Reduction

The earth has plenty of water, but only a small percentage is usable by humans. Of the total water on earth, 96.5% is in oceans and only 2.5% constitutes the fresh water that we need for drinking and for irrigation of farm fields. Ice sheets and glaciers on Earth hold 68.5% of all fresh water, and over 30% of the fresh water is found in ground water (Stephens et al., 2020). As a result, less than 1% of all the fresh water on earth is accessible to humans for drinking, irrigation, and other use (Stephens et al., 2020). The World Health Organization (WHO, 2022) reports that over 2 billion people live in water-stressed countries, which is expected to be exacerbated in some regions as a result of climate change and population growth. In addition to the scarcity of fresh water on earth, human activities contaminate and waste the available fresh water through urbanization, population growth, agricultural activities, and more (Páll et al., 2013). In many urban areas, there is an increase in concentration and use of chemical products, which adversely affects ecological integrity (Brooks & Conkle, 2019). As aquatic ecosystems are threatened, human access to safe water diminishes.

Mass production of artificial milk formula contributes to the degradation of waterways, resulting in water pollution unable to support the healthy aquatic life (Smith, 2019). Water usage is present throughout the process of artificial milk formula production. Dairy cows, which produce the milk extracted for artificial milk formula, graze on pastures that require watering (Davidove & Dorsey, 2019). An estimated 800 L of water is required to produce 1 L of cow’s milk (Davidove & Dorsey, 2019). During manufacturing and distribution of artificial milk formula, water and energy are used. This includes the energy needed to heat water for sterilization, remove water for conversion to powder, and rehydrate the powder for feeding (Davidove & Dorsey, 2019; Karlsson et al., 2019). The water footprint of milk powder is approximately 4700 L/kg (Joffe et al., 2019). According to this estimate, breastfeeding an infant for 6 months can potentially save up to 105,280 L of water (Davidove & Dorsey, 2019). The water footprint accounted for to generate 1 kg of artificial milk formula powder would include water needed to grow a field adequate for grazing, feed cows, and support factory operation from farm to store. Although most of these processes use water, about 80% of it can return to the ecosystem in the form of wastewater; however, this returned water would not be the fresh water that humans need for drinking, further reducing the less than 1% fresh water reserve on earth (Upkeep Technologies, Inc., 2023). It is imperative that we focus on water conservation as scarce water resources are threatened with the rise in global drought risk (Moglia et al., 2018).

Breastfeeding and Natural Birth Interval

Inter-pregnancy interval or birth spacing is the time between a live birth and the conception of another child. Both short and long inter-pregnancy intervals are associated with adverse health outcomes (Sridhar & Salcedo, 2017). To reduce health risks to infants and postpartum women, the WHO recommends birth spacing between consecutive live births be 3–5 years (Molitoris et al., 2019; WHO, 2005). Researchers have shown the elevated risk of infant mortality in both shorter than 36 months and longer than 60 months birth intervals (Molitoris et al., 2019). The direct relationship between short birth intervals and mortality has been consistent. Shorter birth intervals interfere with women’s full recovery from the immediate past pregnancy. In low-income countries, breastfeeding-pregnancy overlap is not rare, which may influence the quality and quantity of breastmilk for the child born following the interval. In these cases of breastfeeding-pregnancy overlap, women often tandem breastfeed their infant and older child (Rosenberg et al., 2021). Although researchers of recent studies show the adaptive role of human milk and similar macronutrient composition of colostrum and mature milk between tandem and non-tandem breastfeeding, there is an undeniable sibling competition for the same resources, for example, parental attention and investment and breastmilk (Rosenberg et al., 2021; Sinkiewicz-Darol et al., 2021). Sibling competition, maternal physical depletion, and infectious transmission are thought to link infant mortality and short birth intervals (Molitoris et al., 2019).

Breastfeeding assists in fertility control by providing natural birth spacing. During breastfeeding, two hormones are in action: the prolactin hormone to stimulate milk production and the oxytocin hormone to eject milk from the breast. Nipple stimulation from breastfeeding releases a high amount of prolactin hormone. The prolactin inhibits ovulation and results in postpartum amenorrhea, therefore lengthening the interval between births (Labbok, 2008). For this reason, breastfeeding women may select lactational amenorrhea method which does not disrupt lactation and is satisfactory for the couple, as a contraceptive method to achieve optimal birth spacing (Berens & Labbok, 2015). On the other hand, a woman with a short duration of breastfeeding could experience short birth spacing as a result of low prolactin concentration (Labbok, 2008). In a meta-analysis conducted in Ethiopia with nine studies, the researchers reported a 46.95% prevalence of short birth spacing among reproductive-age women and odds for association between the duration of breastfeeding and short birth spacing of 16.9 (Damtie et al., 2021). Close birth spacing increases population growth, decreases women’s productivity, and increases the demand for natural resources, ultimately contributing to threats to global food system sustainability. Although breastfeeding alone is not enough to eliminate close birth spacing, breastfeeding exclusivity and duration do have a positive association with longer times between pregnancies.

Discussion

The current research reviewed in this study suggests that in recognition of the role of breastfeeding on the Earth’s resources, it is time to shift the focus of breastfeeding promotion efforts from only health, economic, and social benefits to also include environmental stewardship in breastfeeding and particularly exclusive breastfeeding. Infant feeding practices are also important. The use of bottles for feeding has a negative impact on the environment because discarding the equipment purchased for pumping, storing, and feeding has an environmental cost (Becker & Ryan-Fogarty, 2016). While environmentally meaningful, it is important to note that there are cases in which bottle feeding of mother’s own milk or human milk is necessary, including when the parent and child are not together, for example, working and breastfeeding, or conditions that require additional support, for example, some medical situations during feeding.

Food system sustainability is not typically considered in lactation education. Education and awareness campaigns relating to breastfeeding’s role in food system sustainability are needed for lactation counselors, midwives, and healthcare providers, as well as for the general public and policy makers. Creating an environment through policy conducive to direct nursing may support parents who desire to do so, including daycares near to the workplace for easy access, or infant visits allowed in the workplace for nursing, and kindness toward public nursing. Culturally-appropriate awareness and intervention campaigns are needed to create a nursing environment friendly to direct nursing at the breast.

Worldwide restrictions on traveling and economic activities during the pandemic resulted in drastic reduction in greenhouse gas emissions. However, this decline was temporary and the need for a return to a normal and stabilized economy rendered a rapid increase in emissions (Kumar et al., 2022). To reduce greenhouse gas emissions permanently, a redesign of vital policies toward greener economies is needed. Some suggestions made in the reviewed articles included using renewable energy sources to manufacture the artificial milk formula needed for specific purposes (Long et al., 2021), and reusing ready-to-use artificial milk formula waste from hospitals for animal feed and on-site and off-site composting (Ryan-Fogarty et al., 2017). However, the most direct solution for sustaining the environment is the promotion of breastfeeding exclusivity for the recommended duration and continued breastfeeding up to 2 years and beyond.

Breastfeeding promotion campaigns and policies have a role to play in environmental stewardship. Promotion campaigns could include messages discouraging non-specific artificial milk formula production altogether to reduce the total carbon footprint from unnecessary artificial infant formula production and feeding. Future research is needed to monitor the marketing of artificial milk formula and dietary guidelines in the light of climate and health changes. This would include the continued development of strategies to encourage the use of dietary guidelines as healthy plant-based eating reduces the total carbon footprint and positively contributes to food system sustainability (Binns et al., 2016).

To facilitate exclusive and continued breastfeeding for working parents, there is an urgent need for maternity leave policy modifications. Modifications could entail either full-paid maternity leave, or return-to-work policies that facilitate infants in the workplace with the mother at all times for the full duration of recommended breastfeeding. Until these provisions can be made for breastfeeding parents when they return to work, the negative impact on the environment of forced parent–infant separation, resulting in the need to provide expressed milk and/or artificial milk formula bottle feedings to the child, is inevitable.

Although the full impact of a global pause in the improvement of breastfeeding rates on food system sustainability still needs to be assessed, and there is little doubt that the consequence of not-breastfeeding extends to long-term negative associations with maternal and infant morbidity and mortality, environmental stewardship, and global food security. Increasing breastfeeding is also a WHO goal to solve the double burden of malnutrition and obesity. It is noteworthy that the increase in greenhouse gas emissions from artificial milk formula production intensifies the global synergistic epidemic, that is, syndemic, a situation in which two or more interrelated biological factors work together to make a disease or health crisis worse. A syndemic situation where health and nutrition problems caused by not breastfeeding interacting with climate change could worsen the mounting threat to global food system sustainability (Dadhich et al., 2021; Rosenberg et al., 2021).

Limitations

Given the recency of the concept of the cost to the environment of not breastfeeding, studies examining the connection between breastfeeding and environmental stewardship included in this review were limited and thus limited the review. The articles covering this specific intersection covered breastfeeding in relation to health, social, and economic benefits. The diversity of information about breastfeeding included in this review could have increased the complexity of the summary.

Conclusions

Breastfeeding provides powerful health benefits for nursing parents and infants and is an environmentally sustainable source of nutrition. The cost of not breastfeeding is monumental from the perspective of the food system sustainability and environmental stewardship. The cost is higher in areas facing challenges regarding available safe freshwater and rapid population growth. Given the amplified greenhouse gas emissions produced by the manufacture and use of artificial milk formula and ancillary material manufacturing, it is imperative that national food policy and dietary guidelines promote breastfeeding and its exclusivity as a sustainable diet. This will be most effective if it is coupled with decarbonizing artificial milk formula processing through advocating renewable resources in their manufacture.

Footnotes

Acknowledgements

The authors acknowledge the graduate associates who assisted with manuscript formatting.

Author Contributions

Yeon Kyung Bai: Conceptualization; Data curation; Formal analysis; Methodology; Project administration; Resources; Software; Supervision; Validation; Writing – original draft; Writing – review & editing.

Manar Alsaidi: Data curation; Investigation; Methodology; Resources; Writing – original draft; Writing – review & editing.

Disclosures and Conflicts of Interest

The authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Yeon Bai is an associate editor for the Journal of Human Lactation.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Yeon Kyung Bai

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