Scoping review of climate drivers on maternal health: current evidence and clinical implications

Abstract

Objective

To systematically review the literature on associations between climate drivers and health outcomes among pregnant people. This review fills a gap by synthesizing evidence for a clinician audience.

Data Sources

Systematic scoping review of articles published in PubMed and clinicaltrials.gov from January 2010 through December 2023.

Study Eligibility Criteria

Empirical studies published in English-language peer-reviewed journals, assessing associations between select climate drivers and adverse maternal and birth outcomes. The review included studies examining heat, storms, sea level rise, flooding, drought, wildfires, and other climate-related factors. Health outcomes included preterm birth, low birthweight, small for gestational age, gestational diabetes, pre-eclampsia/eclampsia, miscarriage/stillbirth and maternal mortality.

Study Appraisal and Synthesis Methods

The scoping review protocol was registered with the International Platform of Registered Systematic Review and Meta-analysis Protocols (INPLASY202410004, January 3, 2024) and conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Data were extracted by 2 authors; quality and risk of bias was assessed independently.

Results

Total of 966 references were screened; 16.35% (k=158) met inclusion criteria. The majority of studies (146/158; 92.4%) documented statistically significant and clinically meaningful associations between climate drivers and adverse perinatal health outcomes, including risk of preterm birth, low birthweight, and stillbirth as well as preeclampsia, gestational diabetes, miscarriage, and maternal death. Among the most durable findings: extreme heat exposure in early and late pregnancy were associated with increased risk of preterm birth and stillbirth. Driven in part by large (often population-based) studies and objective outcomes from surveillance data or medical record reviews, studies in this scoping review were evaluated as high quality (scoring 7-9 on the Newcastle-Ottawa Scale). Risk of bias was generally low.

Conclusions

Climate drivers are consistently associated with adverse health outcomes for pregnant people. Continuing education for clinicians, and clinician-patient communications should be expanded to address risks of climate change and extreme weather exposure, especially risks of extreme heat in late-pregnancy. Results from this review should inform multilevel interventions to address adverse health effects of climate during pregnancy as well as practice advisories, protocols, checklists, and clinical guidelines in obstetrics.

AJOG Global Reports at a Glance.

Why was this study conducted?

To synthesize evidence at the intersection of climate and maternal health for a clinician audience.

Key findings

Climate drivers are strongly and consistently associated with adverse health and birth outcomes for pregnant people (92.4% [146/158] of studies examined). Among most important findings: extreme heat exposure in early and late pregnancy associated with increased risk of preterm birth and stillbirth.

What does this study add to what is known?

Few climate/maternal health studies published in clinically relevant journals. Medical school curricula, continuing education for clinicians, and clinician-patient communications must be expanded to address risks of climate change and extreme weather exposure. Consider clinical guidelines.

Introduction

The Lancet Countdown's 2023 report on health and climate change cautions about health repercussions of the increasing frequency of severe weather events.¹ This was amplified by the Declaration on Climate and Health from the 28^th Conference of the Parties (COP28, December 2023) to the United Nations Framework Convention on Climate Change in Dubai, endorsed by 151 countries.² These documents fall short of specifically identifying pregnancy as a period of heightened vulnerability to climate-related factors. Instead, they offer only generic mentions of women, girls, and children. Climate drivers such as heatwaves, droughts, and storms are expected to intensify and cause harm to health and well-being through direct and indirect pathways.³ Pregnant people, infants, and young children confront the greatest risk of adverse impacts of climate change, due to biological, social, economic, and environmental factors.

The physiologic and anatomical changes that occur during pregnancy increase risk of harm due to climate change.⁴ This vulnerability is attributed to pregnancy-related changes in thermoregulation and metabolism, as well as cardiovascular, respiratory, and immune systems.^5,6 Climate-related health challenges, including increases in vector-borne diseases, respiratory illness, and malnutrition, adversely impact pregnancy outcomes.⁷ Epidemiological studies clearly link heat and adverse outcomes, including preterm birth,^8,9 low birthweight,¹⁰ gestational diabetes,¹¹ congenital anomalies,¹² stillbirth,¹¹ and preeclampsia.^13,14 There is consensus that a person's ‘exposome’ –lifetime exposures to environmental factors that shape health – begins during pregnancy and is associated with outcomes in childhood.¹⁵

Healthcare providers can educate patients about imminent threats posed by worsening environmental factors. However, incorporating evidence of environmental harms into clinical guidelines has progressed slowly. A recent review of clinical guidelines from 49 global sources found <5% mentioned keywords associated with climate-related exposures (eg, heatwave, air pollution) or related illnesses.¹⁶ Most literature references health system sustainability, medical waste, and preparedness efforts as climate-related issues,17, 18, 19 with recent acknowledgement in obstetrics-gynecology specifically.²⁰ Less attention has focused on recommendations for clinicians, despite their critical role in helping individuals navigate and potentially mitigate adverse health impacts of climate change.²¹

There have been previous narrative reviews on the intersections of climate change and maternal health,8, 9^,13,22, 23, 24, 25 but significant growth in empirical studies since 2020, warrants an updated synthesis. Such findings could be used to inform medical school curricula, continuing education requirements, committee opinions, statements, practice advisories, and clinical guidelines in perinatal care.

Objective

The primary objective is to systematically review the literature on associations between climate drivers and maternal health and birth outcomes (2010 through 2023). This review fills a gap by synthesizing evidence for a clinician audience.

Methods

A protocol for this scoping review was established and agreed to by all co-authors, including search modalities, eligibility criteria, and methodological details. The protocol was registered with the International Platform of Registered Systematic Review and Meta-analysis Protocols (INPLASY202410004, January 3, 2024). The protocol initially included maternal and child outcomes; an update on July 24, 2024, separated the 2 populations given large differences in methodologies and geographical areas of focus.

Eligibility criteria, information sources, search strategy

We conducted a scoping review of articles published in PubMed from January 2010 through December 2023. Search terms included pregnancy outcomes: preterm birth, low birthweight, small for gestational age, pre-eclampsia, eclampsia, gestational diabetes, fetal demise, fetal death, miscarriage, stillbirth, and maternal death. Exposure terms included: heat, drought, food insecurity, climate change, extreme weather, acute weather events, wildfire, forced migration, storm, sea level rise, rainfall, flood. Air pollution was excluded because effects of climate-related pollution often cannot be differentiated from other sources of indoor or outdoor air quality, and reviews on this exposure were recently conducted.26, 27, 28

A secondary search was conducted in clinicaltrials.gov to identify additional studies that met inclusion criteria. Given the range of climate-related exposures (eg, heat, storms, flooding, drought) the variety of health outcomes (eg, preterm birth, low birthweight, stillbirth), and heterogenous study designs, a scoping review gives us a broad lens to identify knowledge gaps, summarize trends, and assess the extent of available research that is less suited to a meta-analysis or systematic review.

Study selection

Three authors independently examined articles for relevance based on title and abstract. Full-text articles then were assessed for inclusion. Reference lists of screened articles and previous reviews were examined for additional studies. Inclusion criteria were assessment of associations between select climate drivers and maternal health and birth outcomes (Figure 1); empirical studies published in peer-reviewed journals; and studies published in English.

Figure 1.

Effects of climate drivers on adverse health outcomes assessed in this scoping review

Masters. Scoping review of climate drivers on maternal health: current evidence and clinical implications. AJOG Glob Rep, 2025.

Data extraction

Data were extracted from eligible studies and stored using Microsoft Excel (version 2312). Characteristics included study design, location, climate driver, sample size, ethnic/racial distribution, data collection, outcomes, key findings and effect sizes for measures of association.

Assessment of risk of bias

Studies were systematically evaluated for bias to determine overall quality and reliability. Most studies were observational (see Table 1 for study categories); therefore, we used the Newcastle-Ottawa Scale, designed to evaluate quality of nonrandomized studies like cohort and case-control designs.²⁹ Higher scores indicate increased methodological quality and lower risk of bias (range=0-9). One co-author (CW) conducted the assessment to evaluate selection bias, comparability, and qualified outcomes for all studies. Two co-authors (CM, JRI) conducted validity checks. There was >90% concurrence; discrepancies were resolved through discussion and consensus.

Table 1.

Summary of included maternal studies (k = 158)

Study attributes	% (N)
Climate factors
Heat	68.35 (108)
Storms, sea level rise, flooding	23.42 (37)
Wildfires	8.23 (13)
Adverse birth outcomesa
Preterm birth (<37 weeks gestation), low birthweight (<2500 grams), small for gestational age	65.82 (104)
Stillbirth	18.35 (29)
Miscarriage	8.23 (13)
Maternal outcomes
Pre-eclampsia and eclampsia	12.66 (20)
Gestational diabetes	3.80 (6)
Maternal death	1.90 (3)
Region of origina
North America	49.43 (78)
Asia	31.64 (50)
Australia	13.29 (21)
Europe	8.86 (14)
Africa	7.59 (12)
South America	3.80 (6)
Global	0.63 (1)
Study methodology
Descriptive	43.03 (68)
Comparison studies	30.37 (48)
Retrospective cohort	10.12 (16)
Time series	6.33 (10)
Prospective cohort	6.33 (10)
Ecological	2.53 (4)
Others	1.26 (2)
Sample size
≤499	5.06 (8)
500–4999	8.86 (14)
5000–19,999	15.18 (24)
20,000–99,999	17.08 (27)
100,000–999,999	40.50 (64)
≥1 million	13.29 (21)

^aNumbers and percentages in the following rows: adverse birth outcomes and region of origin do not sum to 100 due to studies covering multiple categories.

Masters, Scoping review of climate drivers on maternal health: current evidence and clinical implications, AJOG Glob Rep, 2025.

Data synthesis

We extracted the data and assessed effect sizes to gain understanding of strength of associations between specified climate drivers and outcomes. We then sorted hazard ratios, odds ratios, and risk ratios – grouped by exposure and outcome – from minimum to maximum, isolating extreme values (ie, outliers).

Results

Study selection

A total of 966 articles were identified in PubMed (no duplicates). All were screened; 178 full-text articles were reviewed; 158 met inclusion criteria and were included in the review (PRISMA Flowchart, Figure 2). Replicating with all search terms in clinicaltrials.gov, 186 heat-related and 14 flood-related studies were identified. All heat Randomized Controlled Trials (RCTs) were excluded; they either did not assess climate-related heat sources and/or did not include specified outcomes. One flood-related cluster randomized trial was identified (ref: NCT05640063); however results are not yet reported.³⁰

Figure 2.

PRISMA flowchart of selection of articles

Masters. Scoping review of climate drivers on maternal health: current evidence and clinical implications. AJOG Glob Rep, 2025.

Study characteristics

Study characteristics are provided in Table 1. Most (68.35%) studies examined associations with heat as the climate driver, and the most common birth outcomes were preterm birth, low birthweight, and small for gestational age, with many studies examining all 3 concurrently (Figure 3, visual synthesis). One-half of studies (49.43%) were conducted in North America, and the most common methodological design was descriptive (43.03%).

Figure 3.

Health outcomes: association with climate exposures

Masters. Scoping review of climate drivers on maternal health: current evidence and clinical implications. AJOG Glob Rep, 2025.

Risk of bias of included studies

The Newcastle-Ottawa Scale – designed to evaluate quality of nonrandomized studies like cohort and case-control designs – was used to systematically evaluated for bias to determine overall quality and reliability. Most studies were evaluated as high quality (7-9 on the Newcastle-Ottawa Scale), indicating low risk of bias in selection and outcome categories. However, potential confounding bias might exist regarding comparability.

Synthesis of results

Association of climate factors with adverse birth outcomes

Heat

Most studies (68.35%, k=108) examined heat as a climate-related exposure during pregnancy. These were largely descriptive or retrospective cohort studies. Heat-related study terms included extreme heat,³¹ high ambient temperature,³² heatwaves,³³ heat stress, high or extreme temperature,³⁴ and thermophysiological stress.³⁵

There was substantial heterogeneity in heat exposure measurements. For example, mean daily maximum temperature varied by geographic location (eg, ≥24°C in Canada,³⁶ ≥33°C in China³³). One study from Iran considered extreme heat exposure at 45.4°C and used Physiological Equivalent Temperature, an index combining temperature, humidity, wind speed, and radiation.³⁷ Likewise, operational definitions of heatwaves varied, though they typically defined as at least 2 consecutive days with mean daily temperatures above the 90^th-95^th percentile.38, 39, 40, 41

Despite variation in operationalization, nearly all studies documented significant associations between heat and adverse birth outcomes, suggesting consistency of associations: preterm birth (96.6%, 58/60), low birthweight and/or small for gestational age (95.45%, 21/22), miscarriage and/or stillbirth (95.83%, 23/24). Extreme heat exposure was also significantly related to pregnancy complications such as pre-eclampsia/eclampsia (83.33%, 5/6) and gestational diabetes (100%, 4/4), where heat is hypothesized to trigger an inflammatory response increasing risk for these adverse outcomes.

Examining measures of association, heat increases risk for adverse outcomes by as much as 50% to 100%. Across studies that reported effect sizes to describe the associations between heat and these health outcomes, there was moderate increased risk: Odds Ratios (ORs) ranged from 1.06 to 1.79 (95% CI 1.12-2.78 to 1.19-2.71; Relative Risks (RRs) ranged from 1.01 to 2.16 (95% CI, 1.01–3.80 to 1.24–3.76); Hazard Ratios (HRs) ranged from 1.01 to 1.55 (95% CI, 1.00–1.18 to 1.48–1.61).

Extreme heat exposure early in the first trimester and in late pregnancy was associated with increased risk of miscarriage or stillbirth.^35,40,42, 43, 44 However, magnitude of effects was inconsistent even when excluding the most extreme values (ranging from 50% lower risk to 2.5 times higher risk). For miscarriage and stillbirth, range of effect sizes varied: ORs 1.15 (95% CI, 0.92–1.42) to 1.28 (95% CI, 1.03–1.60); HR 0.54 (95% CI, 0.36–0.82) to 1.55 (95% CI, 1.48–1.61); and RRs 1.01 (95% CI, 1.00–1.02) to 2.49 (95% CI, 1.24–5.03). There were also some extreme values (eg, OR 342.99 (95% CI, 295.53–398.06)).⁴⁵ One study described changes in risk of stillbirth as 10.4% per 10°F/5.6°C increase in temperature.⁴⁶

Few studies included maternal mortality as an outcome. Upon initial screening, only 1 high-dimensional computational analysis documented a positive association between extreme heat and pregnancy-related mortality.⁴⁷ However upon closer review, 2 other studies found positive associations for heatwave exposure and maternal nonaccidental death, defined as deaths with no identifiable incident or cause.^38,39

Studies that documented associations between acute and/or chronic heat exposure during preconception or pregnancy with adverse health outcomes were more likely to be larger, longitudinal studies.⁴⁸ Studies in more temperate climates (eg, Sweden) were less likely to document associations.⁴⁹ Women with chronic conditions prior to pregnancy,⁵⁰ at age extremes (eg, <19 or >30 years old),^51,52 and racially minoritized populations,^32,53,54 were more vulnerable to heat effects on adverse birth outcomes. Individuals in higher socioeconomic brackets appear less susceptible to heat effects, likely driven by being less involved in physically demanding jobs and having better access to cooler (ie, air-conditioned) environments.^35,55, 56, 57, 58 With heat exposure, male fetuses were at elevated risk for preterm birth, small for gestational age, and stillbirth in multiple studies.^35,57,59,60

Critical windows of heat exposure. Risk of adverse outcomes varied by trimester for each outcome. Risk for preterm birth and stillbirth were commonly identified with heat exposure in the first or third trimester. Associations between heat and low birthweight were documented throughout pregnancy.^37,61,62 Most research on heat and associations with gestational diabetes and pre-eclampsia/eclampsia pinpoint early pregnancy (≤22-weeks’ gestation)^14,36,63, 64, 65 and third trimester^14,66 as critical windows of exposure. Heatwave exposures late in pregnancy^31,42,55,67 and smaller diurnal temperature range (difference between daytime maximum and nighttime minimum temperature)⁴² may trigger preterm birth and stillbirth; i.e., a smaller temperature range in the context of extreme heat is hypothesized to prevent the body from adequately cooling down during nighttime.⁴² These associations are strengthened with increasing temperatures and duration of exposure.⁶⁷ Heat exposure is associated with increased risk of spontaneous premature rupture of membranes (PROM) as well as decreased uterine blood flow, providing potential biological mechanisms to explain these effects.68, 69, 70

Storms, sea level rise, floods

One in 5 studies (k=37, 23.42%) examined the impact of storms, sea level rise, and flooding in the context of climate change with maternal and birth outcomes. Most (31/37, 83.78%) documented statistically significant associations. The majority of storm-related studies examined hurricanes and tropical cyclones, mostly in the US, with preterm birth, low birthweight, and small for gestational age.71, 72, 73 Many studies examined the impact of storms on disruptions in access to prenatal care and on maternal stress and other psychosocial factors.⁷⁴ One case-control study from Bangladesh identified associations between rising sea levels, drinking water salinity, and risk of preeclampsia and gestational hypertension.⁷⁵

Floods were studied in relation to preterm birth, low birthweight, and small for gestational age (k=6); preeclampsia, eclampsia, and gestational diabetes (k=4); and miscarriage or fetal death (k=2). Study designs were mostly descriptive or included comparison groups, and findings were mixed. Approximately 1-half of studies on storms found weak or no associations with these health outcomes.

Studies that identified a positive association explored displacement by floods and low birthweight^76,77 as well as precipitation and high frequency of storm/flood events combined with higher temperatures and likelihood of preterm birth.⁷⁸ Most consistent were associations with eclampsia/pre-eclampsia. Floods heighten exposure to lead (Pb) in soil, and in zip codes with high Pb accumulation, pregnant individuals were 4 times more likely to develop eclampsia.⁷⁹ Flooding was also associated with prolonged heightened stress—another risk factor for pre-eclampsia.⁸⁰

Excluding 1 outlier examining effect of storms on gestational diabetes,⁸¹ effect sizes for storms, sea-level rise and flooding documented an approximately 50% increased risk of adverse birth outcomes, with no clear exposure window by gestational age. Among studies that documented a positive association, effect sizes ranged from: ORs 1.06 (95% CI, 0.92–1.42) to 1 study reporting 111.8 (95% CI, 16.7–284.4);⁷⁵ RRs 1.01 (95% CI, 1.00–1.02) to 2.49 (95% CI, 1.24–5.03), and HRs 0.54 (95% CI, 0.36–0.82) to 1.55 (95% CI, 1.48–1.61).

Wildfires

Thirteen studies (8.23%) examined wildfires as a climate-related exposure in pregnancy, and all but 1 found a positive association (92.30%). Most examined association of wildfires, and PM_2.5 air pollution caused by wildfire smoke, with outcomes including preterm birth (k=6), low birthweight (k=4), gestational diabetes (k=2), and miscarriage (k=1). Most studies were conducted in the US, Australia, or Brazil.

Studies on wildfires were largely limited to descriptive designs, though some included comparison groups. Most found a positive association with preterm birth and/or low birthweight,82, 83, 84, 85, 86, 87, 88 but not pre-eclampsia.⁸⁵ One study found a positive association with miscarriage.⁸⁹ Some identified a dose-response relationship. One study found that each additional day of moderate to high intensity wildfire smoke exposure during pregnancy increased the risk of preterm birth, with a 3.4% rise over a 7-day exposure period compared to those unexposed.⁹⁰ One study found for each 1-μg/m3 incremental increase in average concentration of fire-related fine particulate matter (PM_2.5) during pregnancy, there was a 5.1% increased risk of fetal loss (95% CI, 1.03–1.07).⁸⁹ The first trimester formed a critical wildfire exposure window for vulnerability to preterm birth, small for gestational age, and low birthweight.^82,91,92

Comment

Principal findings

Climate drivers, particularly extreme heat, have a significant impact on the health and birthing outcomes of pregnant people. Our review of 158 studies revealed that 92.4% documented significant associations between a climate driver—heat, storms, sea level rise, floods, or wildfires—and 1 or more adverse health outcomes across the perinatal period. Two-thirds of the studies in this scoping review addressed heat as an exposure (k=108). Despite substantial heterogeneity in measures of heat exposure (eg, absolute temperatures, heatwave days), ≥95% of studies documented a significant association between heat and preterm birth, low birthweight, small for gestational age, miscarriage and/or stillbirth. The majority of studies that examined the impact of storms, sea level rise and/or floods (31/37 studies; 83.78%) as well as wildfires (12/13 studies, 92.30%) also documented associations with adverse perinatal health outcomes.

To inform meaningful action, this review also identified critical windows of heat exposure—most often in early or late pregnancy—that altered vulnerability. Although heat exposure was linked with adverse health at any stage of gestation, the final month—and especially the final week—of pregnancy were critical windows for extreme heat, with the risk of preterm birth and stillbirth increasing with prolonged exposure. Extreme heat exposure is hypothesized to trigger an inflammatory response that acts as an environmental stressor; this is supported by observations that extreme or prolonged heat exposure are associated with preterm birth within 1 week of that exposure as well as a significant increase in risk of severe maternal morbidity.⁹³

Comparison with existing literature

This scoping review included studies from 2010 to 2023. However, recent years have seen exponential growth in research addressing climate drivers on maternal health, with 44% of studies published between 2020 and 2023, which few prior reviews have captured. The most recent reviews have tended to focus on 1 set of environmental exposures such as extreme temperature^9,94 or air pollution²⁴ only. This scoping review is more comprehensive, examining multiple climate-related exposures such as heat, flooding, and wildfires. Moreover, we conducted a thorough review of all empirical papers in PubMed and clinicaltrials.gov.

Most studies reviewed were published in public health journals, as well as those specializing in environmental science, epidemiology, social sciences, economics, and general science. Only 13% of publications were published in clinical journals, highlighting the importance of disseminating these findings to clinician audiences, as we aim to do here. Our recommendations target individual-level interventions in the context of clinical interactions and health communications as well as system-level interventions for programs and policies (see below).

Recent systematic reviews on these topics emphasize that individuals in lower socioeconomic groups, racial minorities, and those with chronic conditions and at age extremes are most vulnerable to adverse pregnancy outcomes due to extreme heat exposure.⁸ While our review did not directly examine the influence of social determinants of health, our findings—namely, that climate drivers are associated with adverse maternal and birth outcomes—complement prior work. Collectively, these results should compel obstetricians to recognize the health impacts of climate change, particularly for those who are most vulnerable, such as individuals in lower socioeconomic groups, racial minorities, those with chronic health conditions, and those who are pregnant in their teenage years or at advanced maternal age.

Strengths and limitations

Many studies utilized large, population-based datasets sourced from hospital or governmental records, ensuring representative samples and reliable measures of exposures and outcomes. Longitudinal designs, often spanning more than a decade, offered comprehensive insights into long-term trends and outcomes. Furthermore, the focus on environmental and ecological data, such as temperature and precipitation, provides valuable insights into the impact of climate on perinatal health. Cohort study designs were the most common, enabling exploration of temporal relationships between exposures and outcomes.

Limitations include a reliance on ecological data at large geographical scales (city/county/state/province), potentially overlooking local micro-climates and household effects (eg, availability of air conditioning). Many studies did not fully account for potential confounders such as socioeconomic status, housing quality or pre-existing health conditions. Additionally, the majority of studies included were observational, limiting our ability to infer causal inference, and mechanisms of association are often not explored in depth, indicating a need for further research to clarify causal pathways. Further, while some studies considered trimester-specific exposure differences, acknowledging the importance of timing of exposure in pregnancy, many did not. This remains an important area of future research, in service of identifying whether interventions disseminated at particular stages of pregnancy may alleviate risk. Lastly, heterogenous definitions of heat exposure limit the generalizability of our findings.

These limitations underscore the challenges in translating research findings into practical clinical interventions and targeted practice advisories, protocols, checklists, and/or clinical guidelines. Future research needs to identify the causal pathways linking climate drivers to health outcomes and establish clear thresholds for safe exposure, while also evaluating the implementation of effective mitigation strategies. Research on heat and pregnancy outcomes are most consistent. Findings were mixed for other climate drivers and their impacts across the perinatal period. Given the increasing frequency and severity of floods, storms, and wildfires, future research should prioritize addressing these gaps and developing targeted interventions to mitigate their adverse effects on perinatal health.

Conclusions and implications

The National Institutes of Health's (NIH) Climate Change and Health Initiative Strategic Framework (2022) warns that despite mounting evidence, little has been done to protect pregnant people and infants from the impacts of extreme temperatures.⁹⁵ Global temperatures reached new record highs for 2 consecutive days in July 2024; July 2023 through August 2024 have been hottest months on record; and the decade from 2015 through 2024 has experienced the highest annual maximum global-average daily temperatures.⁹⁶ For obstetricians, understanding associations between heat exposure and health is imperative to provide quality care to pregnant individuals. While some initiatives exist that work to provide information related to heat risks specifically for pregnancy,⁹⁷ a more coordinated effort—inclusive of the clinicians who care for pregnant people, hospital systems that facilitate this care, and legislators and others responsible for changing public policy—is necessary to ensure consistent and widespread dissemination of tailored health information regarding climate-related risks.

As the perinatal period offers more opportunity for birthing people to engage with the healthcare system, we echo calls from Samuels and colleagues for more precise clinical recommendations regarding climate change factors and maternal health.⁶ For example, despite guidelines warning pregnant individuals around heat exposures from hot tubs, baths, and exercising outdoors, no clear advice is given on safe exposures to ambient heat.⁶ The American College of Obstetricians and Gynecologists (ACOG) recommends the use of clinical guidelines, protocols and checklists to improve outcomes, and suggests that obstetrician–gynecologists be engaged in the process of developing these guidelines to create consensus, promote adherence, and improve quality of care.⁹⁸

Climate change as a macro-level issue and the heterogeneity of study methodologies likely contribute to hesitancy regarding the translation of existing evidence into clinical guidelines, protocols or care pathways. This unfortunately results in a lack of meaningful action. Results of this scoping review document that climate exposures such as heat, flooding, and air pollution are associated with a broad array of adverse perinatal outcomes. Therefore, we recommend development and implementation of standardized, evidence-based clinical guidelines or other protocols and checklists—including interventions that can be implemented at the both the individual- and systems-levels; examples of each are provided in the following sections.

Individual-level interventions: clinical interactions and health communications

Obstetricians are a primary source of information for pregnant people. They are trusted sources who help contextualize risk in relation to other individual factors, such as comorbidities, medications, and other pregnancy-related complications. Contact between healthcare providers and pregnant individuals typically increases throughout gestation with bi-weekly visits from 28 to 36 weeks, followed by subsequent weekly visits.⁹⁹ As such, obstetricians are well-poised to assist patients in mitigating the risks of heat exposure during the later stages of prenatal care. ACOG also recommends assessing for environmental exposures in the patient history during prenatal care¹⁰⁰ to identify those most vulnerable. The Heat-Related Illness Screening Tool (HIST) for heat-related illness in pregnant people has been validated for use in community screening.¹⁰¹ Minimally, clinicians should advise pregnant patients to stay indoors during heat waves, keep their homes cool with increased ventilation (fans) or air conditioning particularly at night, wear light clothing, and stay hydrated.

Obstetricians should also provide practical advice to patients in wildfire-affected areas to mitigate their wide-ranging health and socioeconomic impacts.¹⁰² This could include ‘grab and go’ bags with essential items, increasing use of certain medications such as bronchodialotors where appropriate, educating patients about air pollution monitoring and staying indoors when PM_2.5 exposures are dangerous.¹⁰²

Aligned with the importance of clinician-patient health communication, recent U.S. government initiatives have prioritized communicating the health effects of climate change, providing specific guidance for pregnant individuals and children. As of April 2024, the U.S. Centers for Disease Control and Prevention (CDC) website now offers a localized heat risk tool (HeatRisk) to guide pregnant individuals and families in managing risks as they relate to extreme heat and air quality.¹⁰³ The Environmental Protection Authority added comprehensive advice to pregnant and postpartum women on climate specific risks to health in late 2023.¹⁰⁴

System-level interventions: programs and policies

There is growing consensus that clinicians and health systems must provide climate-informed care.¹⁰⁵ Training obstetricians to address health impacts of climate change is crucial to integrate climate-informed practices into routine prenatal care, protecting patients from risky exposures during the perinatal period. For example, Harvard Medical School recently implemented a Climate Change, Environment, and Health framework to prepare medical students to understand the physical and social health concerns associated with climate change.¹⁰⁶ To date, these training efforts lack broad implementation.

Another example of a systems-level intervention is the Clean Power Prescription program at Boston Medical Center (BMC). Households enrolled in their Medicaid managed care program receive monthly credits to contribute to energy bills so recipients can maintain safe household temperatures during periods of high ambient heat, relying on sustainable energy generated by BMC-managed solar panels.^105,107

A cluster randomized trial in Pakistan is underway to assess effectiveness of newborn and delivery kits designed to reduce perinatal mortality which is heightened during floods that disrupt healthcare access.³⁰ Results are pending, yet this practical approach may help identify evidence-based solutions to mitigate impacts of climate-related risks on maternal and neonatal health, especially in low resource settings.

Policy-level interventions also can be employed to designate areas as “climate change risk zones,” enabling the US Department of Health and Human Services to allocate funding to train clinicians to manage climate-related health risks. Policy proposals have been introduced in Congress to support these types of initiative (eg, 2023 Protecting Moms and Babies Against Climate Change Act); however legislation has not yet been passed.¹⁰⁸

In conclusion, this scoping review found that climate drivers—particularly exposure to extreme heat—have statistically significant and clinically meaningful impacts on the health and birthing outcomes of pregnant people, with strong associations for preterm birth, low birthweight, small for gestational age, miscarriage, stillbirth, gestational diabetes, and pre-eclampsia/eclampsia. Findings suggest that obstetricians and other prenatal care providers should assess and assist pregnant people to mitigate and adapt to the risks of extreme heat exposure and other adverse climate drivers, especially early and late in gestation. Targeted, individual-level clinical interventions in tandem with broader systems-level change may reduce climate change-related health risks across the perinatal period.

CRediT authorship contribution statement

Claire Masters: Writing – review & editing, Writing – original draft, Validation, Supervision, Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Chuhan Wu: Writing – review & editing, Writing – original draft, Visualization, Validation, Investigation, Formal analysis, Data curation. Dara Gleeson: Writing – review & editing, Writing – original draft, Validation, Data curation. Michaela Serafica: Writing – review & editing, Writing – original draft, Investigation, Data curation. Jordan L. Thomas: Writing – review & editing, Writing – original draft, Validation, Investigation. Jeannette R. Ickovics: Writing – review & editing, Writing – original draft, Validation, Supervision, Project administration, Methodology, Data curation, Conceptualization.