Climate change is a major threat to human health, with inequitable and unjust risks to neonatal health.1,2 As climate change worsens, so too do its consequences, including loss of biodiversity, greater frequency and intensity of severe weather events, and further environmental degradation.3 The negative human health implications are considerable, with disproportionate consequences for infants and young children whose developing bodies make them uniquely vulnerable.4,5 The neonatal health impacts of climate change occur through several pathways (Fig. 1), including exposure to air pollution, extreme temperatures, and severe weather events which worsen food insecurity and malnutrition, water sanitation, and infectious disease transmission. Such exposures affect pregnancy and neonatal outcomes with lasting impacts throughout the lifespan.

Climate change, environmental exposures, and pregnancy outcomes are deeply intertwined. Air pollution, especially small particles such as particulate matter <2.5 µm in diameter (PM2.5), can enter the respiratory tract and other mucosa and cross the epithelium resulting in systemic inflammation and oxidative stress, and affecting hormone levels and gamete quality.6 These mechanisms are hypothesized to contribute to placental insufficiency and may trigger spontaneous preterm birth. Systematic reviews and meta-analyses consistently demonstrate positive associations of air pollution with low birth weight and preterm birth.7 High temperatures affect hormones and fertility,8,9 and increase the risk of pregnancy complications including birth defects, preterm birth, and stillbirth.10

Air pollution and heat are not the only environmental threats to pregnancy health. Multiple chemicals to which humans are ubiquitously exposed contribute to adverse pregnancy outcomes.11 Per- and polyfluoroalkyl substances (PFAS), or “forever chemicals,” are used to manufacture non-stick cookware and stain-resistant furniture and used in food packaging and diapers. Microplastics are tiny plastic particles that originate from the breakdown of larger plastics or are intentionally added to products (e.g., cosmetics, industrial materials). PFAS and microplastic exposure often occurs through ingestion of contaminated drinking water or food. Climate change contributes to increasing PFAS and microplastic releases, with the breakdown of the latter creating greenhouse gases that exacerbate climate change.12 PFAS exposure is associated with preterm birth13 and hypertensive disorders of pregnancy14 which can lead to fetal growth restriction and medically indicated preterm birth. Microplastics can reach the placenta and cause inflammation, oxidative stress, and hormonal disruption, thereby affecting fetal growth and pregnancy outcomes.15,16 Other chemicals, such as phthalates (synthetic chemicals used in consumer and personal care products), polybrominated diphenyl ethers (used as flame retardants in consumer products such as furniture) have been shown to be associated with preterm birth, while metals (especially lead) may also increase risk of preterm birth.17, 18, 19

The physical environment continues to affect infants after they are born. Many of the same environmental exposures that increase the risk of preterm birth also increase the risk of common adverse child health outcomes such as asthma14 and neurodevelopmental disorders such as autism spectrum disorder,20 and can contribute to skin irritation.21 These conditions are also more common among preterm infants.22,23 Emerging evidence suggests that environmental exposures may exacerbate morbidities of prematurity. In a 2024 analysis of a Philadelphia cohort of infants with bronchopulmonary dysplasia, the most common medical morbidity of extreme preterm birth, higher ambient PM2.5 exposure was associated with emergency department visits and hospital readmissions for acute respiratory illnesses.24 Another study drawing on data from a prospective pregnancy cohort across 10 Canadian cities found that prenatal exposure to PM2.5 was associated with higher rates of respiratory distress requiring intervention and NICU admission.25 A 2024 study in Rhode Island demonstrated that infants <32 weeks of gestation were at higher risk of elevated blood lead levels than the general population and that elevated lead levels in this sample were associated with poor sleep,26 a known risk factor for impaired cognitive performance.27

Access to safe water has notable implications for infant health, as contaminated water sources, particularly following natural disasters, can affect the health of mothers (e.g., risk of infection) and increase risk of miscarriage, birth complications, and low birth weight.28 Contaminated water also exposes infants to pathogens through bathing or formula feeding both in the neonatal intensive care unit (NICU) and after discharge,29,30 with exposure affecting gut health and inflammation.31 Higher water temperatures contribute to waterborne diseases (e.g., diarrhea, hepatitis) as well as vector-borne diseases, which infants and young children are more susceptible to, given their immature immune systems and developing bodies.32

The impact of climate-related heat on infants born preterm is largely unknown. A 2024 California study demonstrated that heat wave exposure was associated with emergency department visits in the first year of life among full term, but not preterm, infants, although estimates were imprecise for preterm infants.33 Further work is needed to understand the impact of heat on preterm infants, particularly in regions or households with limited access to air conditioning. These data will inform clinicians caring for these infants, enabling evidence-based guidance to share with families on how to minimize exposures and mitigate effects of harmful environments. This is especially important for the most vulnerable infants who require intensive care after birth in NICUs.

Further complicating environmental perinatal health effects, hospital and NICU care unfortunately can contribute to worsening environmental exposures and pollution. Many chemical exposures are necessary to keep preterm infants alive. There is nearly ubiquitous exposure to plastics in the form of nasogastric, endotracheal, or intravenous tubing, and multiple chemical exposures through medications and transfused blood products. Determining ways in which infants can be exposed to materials with the lowest toxicity is an area of research for a few neonatal environmental health researchers.34,35 Finding safe ways to reduce waste, improve efficiency, limit plastic use, and lead by example in our local work environments can also have far reaching impacts.36 It is incumbent upon health systems and NICUs to minimize waste and maximize energy efficiency to minimize toxic exposures.30

Some regions of the world are disproportionately affected by climate change in terms of resources to support climate-resilient healthcare facilities and disaster preparedness. For example, a study of facilities in urban Ghana found that some facilities were six degrees Celsius warmer at night than recorded weather reports due to buildings’ capacities for moderating temperatures and urban heat island effects.37 Given that neonates and infants struggle with heat stress, thermoregulation, and dehydration in high temperatures38,39 and are vulnerable to poor humidity levels,40 planning is necessary to ensure NICU facilities are prepared to function as ambient temperatures and humidity increase. In the face of climate disasters, healthcare facilities face a range of challenges, including low staffing, equipment, and supply shortages, to difficulties with patient transport and hospital system needs (e.g., power, water, communication).41 For example, a study of NICUs in U.S. regions affected by wildfires shed light on the need for stronger NICU disaster preparedness responses and evacuation plans.42

Climate change has profound impacts on social, structural, and environmental determinants of health, exacerbating inequalities in access to resources, healthcare, safe living conditions, and toxic exposures. Communities that already experience greater health risks due to social and economic inequities, including people whose incomes are below the federal poverty threshold, Black, Indigenous, Pacific Islander, Asian, and Latine communities, and rural communities, are more susceptible and disproportionately exposed to climate hazards due to environmental racism and segregation.43, 44, 45 These communities have fewer buffers and resources to counteract such exposures, such as green space and trees that can help filter air pollution or residential air conditioning. Thus, extant health disparities are made worse by climate-related events. In most parts of the world, including in the U.S., the communities disproportionately exposed to environmental pollution and toxicants also have the highest rates of preterm birth.46,47 It follows that environmental exposures may explain part of the racial and ethnic as well socioeconomic disparities in preterm birth.48 Toxic environmental exposures, socioeconomic stressors, and discrimination also culminate in disparities in medical comorbidities that contribute to disparities in preterm birth. The same exposures that lead to preterm birth are experienced by preterm infants after NICU discharge. This situation presents an opportunity to intervene and contribute toward health equity. Investment in communities through neighborhood greening efforts, structural repairs of housing, subsidizing air conditioning, offering air quality monitors and air purifiers, all represent potential interventions that could improve preterm infant health outcomes. Implementation research to study the effectiveness, feasibility, equity, and scalability of such interventions is key to successful trial design and ultimate impact.49

The drivers of climate change are complex and vast, arising from nearly every facet of life from the level of the individual to the scope of international societal and political systems.50 Similarly, the consequences are expansive and existential. In this complexity, the question of how to ethically respond to global climate change and environmental degradation (hereafter “climate change”), is a major bioethics concern. First, we will consider a principlist approach with a focus on justice. Second, we will consider virtue ethics. Finally, we will consider if current theories fail to include these concerns within the domain of bioethics.

Principlism, the prevailing bioethics framework in the US for the past half century, is based upon the four principles of autonomy, beneficence, nonmaleficence, and justice.51 In considering the fetal or neonatal patient, autonomy is replaced by parental (or surrogate) authority, which is similar but with greater restrictions in place for protection of minors.52, 53, 54, 55 As typically utilized, the framework focuses on the impact of medical decisions at the level of the individual patient.56,57 When viewed broadly as an existential threat to all humanity, it may be difficult to assess climate change through the lens of priniciplism.58 The most relevant consideration within a principle-based approach may be justice, due to the disparate impacts of climate change on different individuals and populations.

Justice as a principle may provide a helpful lens to evaluate why bioethics broadly requires a focus on climate change, because its impacts are not evenly distributed.59 Justice is the moral obligation to treat individuals fairly and equitably with regard to the allocation of benefits, risks, and responsibilities. While there are many conceptions of precisely what justice entails, we focus on egalitarian justice and distributive justice. Egalitarian justice underscores that all individuals have an equal claim to certain fundamental goods or opportunities - in the case of bioethics, these include claims for good health, basic well-being, and access to care. Distributive justice emphasizes that resources and burdens are allocated not simply along equal lines, but also accounting for need, vulnerability, and potential for benefit.51

Negative consequences are most severe for marginalized communities who already suffer from greater health risks associated with limited resource access, income inequity, and racial and ethnic disparities.45,60 For example, an assessment of US pollution inequity assessed pollution-generating consumption against exposure to air pollution.61 They found that, overall non-Hispanic white populations had a “pollution advantage” experiencing less pollution exposure than caused by their consumption, while Black and Hispanic populations had a “pollution burden” with excess pollution exposure relative to their consumption. In the argument for the inclusion of environmental health as a bioethics concern, Ray and Cooper argue that we must extend the “bioethics concept of fiduciary duty to children in an environmental justice context as a matter of justice.”62 A bioethical commitment to the just care of patients then necessitates careful attention and dedication to the disparate effects of climate change upon diverse populations. Promotion of not only equitable access to care for the effects of climate change, but also addressing the upstream negative health drivers is central to a justice-oriented healthcare approach broadly. Health justice is environmental justice.

The principle of justice may also help define why climate change must be seen as a bioethical priority for the field of neonatology specifically. The temporal dynamics of climate change impact neonates in a particular and unique way, both immediately and in the future. With immature immune systems and higher physical and developmental susceptibility to environmental exposures, fetuses and neonates physiologically stand to suffer higher consequences to their health in the present. This disproportionate burden is not limited to now. Current actions to address or mitigate climate effects—or especially a failure of action—may intensify future negative consequences and their multi-level costs. Neonates are impacted disproportionately in compounding ways: 1) they may live longer and as such experience the current costs more intensely and for longer duration; and 2) they may be set up to face even worse consequences that have not arisen yet due to inadequate action. Effects are inequitably centered on neonates in terms of number, intensity, and very uniquely, duration of risks. While all health justice is environmental and climate justice, neonatal health justice carries a unique valence that needs special attention.

The bioethics framework of virtue ethics may provide an alternative argument for why climate change is specifically a bioethical issue. Virtue ethics focuses on the character and virtues of an individual actor.50 The virtues are acquired traits or habits that bring about good or are aimed at some chief good. Individuals operate within practices, institutions, and histories that help define the content and goal of virtues – about what is good, and how to achieve that good. A virtuous clinician or healthcare system is one that embodies actions and habits aimed at health. Examples include courage, honesty, compassion, care, and justice.63 The embodiment and enactment of the virtues towards health not only seek to obtain that goal, but also give ongoing validation, sustenance, and justification of the practice of medicine itself. It is by these virtues that medicine remains medicine. Conversely, when these virtues are not sought or performed, the practice collapses.64 For example, a lack of honesty deteriorates the trust necessary for a vulnerable patient to open themselves up for the care of the medical team. Lack of compassion leads to patients being treated as customers, with healthcare being reduced to business transactions.

Climate change—and its breadth of direct and indirect negative impacts on health—may be viewed within a framework of virtue ethics. As described in this manuscript, a growing body of research intimately links climate change to negative impacts on health. From changes in infectious disease virulence to mental health consequences, climate change has serious health effects. Health is the central goal of medicine, with its virtues necessarily oriented towards its continuation and restoration. Therefore, the virtues must necessarily expand to encompass climate. For example, courage, compassion, and honesty must be directed towards climate action, as this is constitutive of promoting health. In a virtue ethics framework, such virtues are of value both for the intrinsic value of health directly stemming from climate change-informed actions and in support of the instrumental value of medicine as a practice that sustains health.

Both principle-based ethics and virtue ethics may identify climate change as a bioethics issue. In doing so, these frameworks can help focus the moral responsibility and attention of healthcare systems towards addressing efforts to address environmental degradation, while also providing conceptual tools to enact change. However, it must be recognized that existing frameworks might in fact be inadequate to conceptualize climate change as the major bioethics problem of our time. Both the justice-based principlist and the virtue ethics approaches as described above could be criticized as so expansive as to be approaching meaninglessness: if we include climate change, then we must include everything that possibly impacts health. However, it may be possible that the magnitude of risk from climate change—exceedingly, unimaginably high—may make it qualitatively different from other domains with impacts on health. If this is true, then either climate change falls outside bioethics’ scope or a foundational shift is required, one that may require nothing less than a new theory of bioethics able to include the existential challenges of climate change.56 The outline of such a new bioethics is beyond the scope of this paper, but will doubtless require a broader understanding of justice that appreciates humanity and health as within, not outside, the natural world.65,66

Environmental and climate change policies will play critical roles in protecting neonatal health at various stages. In taking an upstream approach to public health, proactive policies must be implemented which address root causes of climate hazards in order to prevent climate impacts that negatively affect fetal and infant development. Given that newborns are susceptible to climate change due to their unique physical and social vulnerabilities, policy and advocacy efforts focusing on reducing climate exposures can help foster healthier outcomes and mitigate long-term disparities that begin early in life.

Environmental policies to protect neonatal health may include those that limit pollutants, including air toxicants, heavy metals, and endocrine-disrupting chemicals, and increase regulations on emissions from sources of fine particulate matter. The Clean Air Act67 and Safe Water Act68 are two examples of environmental regulations supported by the Environmental Protection Agency in the US to protect air quality and drinking water quality. Climate change policies focused on supporting renewable energy and promoting climate resiliency, such as improving infrastructure and planning for healthcare facilities, also have implications for neonatal health to promote protection against and reduce exposure to climate hazards. The US Department of Energy has put forth recommendations regarding ventilation, lighting, and other structural practices that can improve the health of patients while also reducing energy use.31 Advocacy efforts are also needed to raise awareness of how climate change and environmental exposures affect neonatal health, calling on healthcare professionals and hospital systems to amplify these issues and mobilize support for these policies.

Partnerships locally, regionally, and internationally will create the greatest momentum towards change and ensure that community voices are represented in policy decision making. International climate change law is centered on the United Nations Framework Convention on Climate Change, the Kyoto Protocol, the Paris Agreement, and the Nationally Determined Contributions, all of which are frameworks and agreements to ensure global cooperation in climate action.69 To address environmental and climate change inequities, it is of utmost importance that regional and local policies promote environmental and climate justice, for example providing equitable access to clean air, safe drinking water, and green spaces. Providing funds directly to communities and uplifting existing efforts to establish community-based interventions will increase the availability of environmental health resources, improve early-life health outcomes, and reduce disparities. The Justice40 Initiative70 is one example of a federal effort to promote environmental justice by investing in and bringing critical resources to communities that are on the frontlines of the climate crisis.