Global Temperature Trends

Pregnant workers at world cup venues: A review of occupational risks

Research by Hugi Hernandez, Founder of Egreenews

Executive Summary

This report synthesizes peer-reviewed evidence (2021–2026) on occupational risks for pregnant workers in food service, concessions, and landscaping at major sporting events, with specific application to the 2026 World Cup. The core finding is that occupational heat exposure during pregnancy is associated with a doubled risk of miscarriage and a 26% increased odds of preterm birth during heatwaves . A secondary finding indicates that exposure to dust and passive smoking in food service settings correlates with reduced birth weight and increased cesarean section rates . Critically, data on combined exposures—such as humid heat plus chemical cleaning agents—are absent from the academic literature. The actionable insight for event organizers is that existing workplace thresholds for manual labor (e.g., Wet-Bulb Globe Temperature of 27.5°C) are inadequate for pregnant physiology, requiring proactive, trimester-specific cooling and work-rest regimens.

Introduction

In 2026, the FIFA World Cup will be co-hosted by 16 cities across the United States, Canada, and Mexico, spanning multiple climate zones from the humid Gulf Coast to the arid Southwest and temperate northern venues. An estimated 10,000 to 15,000 temporary food service, concessions, and landscape workers will be employed, a significant proportion of whom will be women of reproductive age. While occupational health standards exist for general workers, pregnant employees face distinct physiological vulnerabilities that are poorly addressed in standard event safety protocols.

This report examines three occupational categories: kitchen workers in high-heat food concessions, restaurant servers with exposure to indoor air contaminants and long shifts, and landscape workers performing outdoor physical labor. The analysis is grounded exclusively in university and peer-reviewed journal sources published between January 2021 and May 2026, spanning nine countries across five continents. Where specific evidence for “World Cup venues” is absent (as no studies have yet been conducted on this specific event), we apply evidence from analogous occupational settings in comparable climatic and economic contexts. The report aims to provide a neutral, data-driven foundation for policy adjustments and worker safety guidelines.

Occupational Heat Exposure: The Primary Risk Factor

Heat exposure represents the most documented occupational hazard for pregnant workers in outdoor and indoor settings without climate control. The physiological mechanism involves competition for blood flow between maternal thermoregulation (skin vasodilation) and the uteroplacental unit, potentially reducing oxygen and nutrient delivery to the fetus . A prospective cohort study of 800 pregnant workers in Tamil Nadu, India, found that women exposed to occupational heat exceeding threshold limit values had a doubled risk of miscarriage (adjusted odds ratio 2.4; 95% CI 1.0–5.7) . The same study reported a 2.3-fold increased risk of any adverse pregnancy outcome (including preterm birth, low birthweight, and stillbirth) among heat-exposed women .

Critical windows of susceptibility have been identified in multiple recent studies. A nationwide Japanese study of 986,207 live births (published March 2026) found that heat exposure during gestational weeks 16–22, peaking at week 19, increased preterm birth risk by 16% (odds ratio 1.16; 95% credible interval 1.13–1.19) . This second-trimester window is particularly relevant for World Cup workers, as many may be employed during early to mid-pregnancy before visibly showing, and thus not identified for workplace accommodations. A French study of 20,904 women (2026) similarly found that mean temperatures of 21.6°C (95th percentile vs. median 13.6°C) during weeks 2–15 were associated with a 199-gram reduction in term birth weight .

“Exposure to extreme heat in pregnancy increases the risk of stillbirth. Out of 20 studies, 19 found an association between heat and stillbirth risk.”

Landscape workers at outdoor World Cup venues face the most direct heat risk. A 2025 systematic review and meta-analysis encompassing 198 studies across 66 countries quantified that each 1°C increase in heat exposure raises preterm birth odds by 4% (95% CI 1.03–1.06), and during heatwaves, the odds increase by 26% (95% CI 1.08–1.47) . The review also found that stillbirth risk increases by 13% (95% CI 0.95–1.34) and congenital anomalies by 48% (95% CI 1.16–1.88) under high heat exposure . Critically, the authors note that 63.3% of included studies were from high-income countries, indicating that these risks are not solely a low-income country problem but apply equally to North American venues.

Specific Occupational Exposures: Kitchens, Concessions, and Restaurants

Indoor food service environments combine multiple hazards that are poorly characterized in the literature relative to outdoor heat. The most robust evidence comes from the Italian NINFEA birth-cohort study (2025), which examined 3,938 nulliparous women and their occupational exposures during the first trimester . The study found that maternal exposure to dust—common in kitchen environments from flour, spices, and airborne cooking particulate—was associated with increased odds of cesarean section (OR 6.99; 95% CI 2.36–25.47) . The same study reported that women exposed to passive smoking at work had an increased likelihood of all analyzed birth outcomes, a finding highly relevant for concessions and restaurants where indoor smoking may occur in designated areas or infiltrate from outdoor smoking zones.

Heat exposure in commercial kitchens presents a distinct risk profile from outdoor heat. Kitchens often combine ambient heat from cooking equipment with high humidity from dishwashing areas and steam generation. A 2026 Chinese study on humidity and pregnancy outcomes found that both low and high humidity increase stillbirth risk, with extreme high humidity’s critical window at gestational weeks 27–33 . The study also revealed an important interaction: high humidity (≥55%) actually attenuates heat-related risk, while dry heat is more dangerous . This suggests that kitchen workers in humid environments may have different risk profiles than outdoor landscape workers in arid climates—a nuance not currently reflected in any unified occupational guideline.

Workload and physical demands also matter. The Italian cohort study found that women who reduced their working hours during pregnancy had increased likelihood of adverse outcomes, potentially reflecting a healthy worker selection bias (i.e., women experiencing difficulties self-select into reduced hours) . Conversely, women performing demanding work were less likely to have preterm birth, suggesting that physically fit workers may be healthier overall—a confounder that complicates causal inference. For restaurant workers, shift work and long standing hours represent additional stressors. A 2024 Indian prospective cohort study measured physiological heat strain indicators, finding that 17.4% of exposed workers had elevated core body temperature after shifts, and 29.6% experienced moderate dehydration (urine specific gravity ≥ 1.020) .

“Maternal exposures to heat and dust were associated with a lower birthweight [β = -160.1 g (95% CI -299.6 to -20.7)] and increased odds of caesarean section [OR 6.99], respectively.”

Landscape Workers: Outdoor Physical Labor in Extreme Conditions

Landscape workers at World Cup venues perform physically demanding tasks including mowing, irrigation, fertilization, and turf management, often during the hottest parts of the day to prepare playing fields and surrounding grounds. The 2026 World Cup will be played from June 11 to July 19, coinciding with peak summer temperatures across all host regions. In southern venues (e.g., Houston, Miami, Dallas, Atlanta, Guadalajara, Mexico City), average maximum temperatures exceed 32°C (90°F) with high humidity; in southwestern venues (e.g., Los Angeles, San Francisco, Seattle, Vancouver), temperatures may exceed 35°C (95°F) with low humidity. Both conditions pose risks via different mechanisms.

The 2026 French study on heat and fetal growth explicitly examined modifying factors, finding that associations between heat and reduced birth weight were stronger in women with low vegetation exposure, low social position, and high contextual deprivation . Landscape workers, while working outdoors, may have higher vegetation exposure than indoor workers, but this is not protective—the study measured vegetation in residential environments, not occupational. More concerning is the observation that high contextual deprivation amplifies heat-related risk, as landscape and food service positions are often among the lowest-paid event jobs, potentially limiting workers’ ability to access prenatal care, cooling breaks, or alternative duty assignments.

An expert review published in BJOG (2024) examined environmental heat exposure and stillbirth in the context of climate change, noting that both short-term heat exposure (days to weeks) and whole-pregnancy heat exposure increase stillbirth risk . The review identified a troubling evidence gap: “There is limited pregnancy-specific guidance within heatwave planning, and no evidence-based interventions have been established to prevent poor pregnancy outcomes” . This finding is directly applicable to World Cup organizers, who are likely operating under general occupational heat standards (e.g., OSHA general duty clause in the U.S.) rather than pregnancy-specific protocols.

The Indian cohort study measured occupational heat exposure using Wet-Bulb Globe Temperature (WBGT), finding that exposures exceeding 27.5°C for heavy workloads and 28.0°C for moderate workloads were associated with adverse outcomes . Many World Cup venues will exceed these thresholds routinely during summer afternoons. Among the 800 participants, 47.3% had high occupational heat exposure, and those women had a doubled risk of miscarriage . Notably, the study included only women engaged in moderate to heavy physical work—exactly the profile of landscape and food service workers.

Vulnerability Windows and Physiological Mechanisms

Research published between 2024 and 2026 has significantly refined understanding of when during pregnancy heat exposure is most dangerous. The Japanese nationwide study (2026) identified weeks 16–22 as the critical window for preterm birth, with week 19 showing peak susceptibility . Subtype analyses revealed even more precise windows: week 16 for extremely preterm birth (<28 weeks), week 18 for very preterm birth (28–31 weeks), and week 19 for moderate-to-late preterm birth (32–36 weeks) . This suggests that a woman employed during her second trimester—potentially before disclosing pregnancy to an employer—faces the highest risk of early delivery if working in hot conditions.

The Chinese study on humidity and stillbirth (2026) identified different windows: extreme heat vulnerability at weeks 32–36 (peak at week 35), and extreme high humidity vulnerability at weeks 27–33 (peak at week 32) . This implies that workers in late pregnancy are at elevated stillbirth risk from heat, while mid-pregnancy workers are at elevated preterm birth risk. The physiological mechanisms differ: heat stress in late pregnancy reduces placental blood flow and triggers inflammatory responses, while early heat exposure may interfere with placentation and organogenesis .

For workplace interventions, these timing differences matter. A landscape worker who is 19 weeks pregnant in June faces preterm birth risk; that same worker at 32 weeks in August faces stillbirth risk. No current occupational guidance accounts for this shifting risk profile across gestation. The French study also identified that adjusting for ozone (O₃) air pollution attenuated some heat associations, suggesting that air quality—often poor around stadiums and highways—interacts with heat to affect pregnancy outcomes . This is particularly relevant for outdoor workers and for concessions workers near loading docks with diesel truck exhaust.

Findings Summary Table

慕 FindingPopulation / SettingQuantified RiskSource Occupational heat exposure doubles miscarriage riskPregnant manual workers, IndiaaOR 2.4 (95% CI 1.0–5.7)Rekha et al., BJOG 2024 Heat exposure increases preterm birth riskMeta-analysis, 66 countriesOR 1.04 per 1°C; OR 1.26 during heatwavesLakhoo et al., Nature Medicine 2025 Critical window for heat-related preterm birthJapanese national cohort (986k births)Weeks 16–22, peak week 19: OR 1.16Terada et al., Am J Epi 2026 Heat reduces term birth weight by 199gFrench cohort (20,904 women)21.6°C vs 13.6°C, weeks 2–15Adélaïde et al., EST 2026 Maternal dust exposure increases C-section riskItalian NINFEA cohort (3,938 women)OR 6.99 (95% CI 2.36–25.47)d’Errico et al., PLOS One 2025 Passive smoking at work linked to multiple adverse outcomesItalian NINFEA cohortIncreased likelihood of all analyzed outcomesd’Errico et al., PLOS One 2025 High humidity risk window: weeks 27–33Chinese birth cohort (244k pregnancies)U-shaped risk, minimum at 55% RHLiu et al., Environmental Research 2026 No established pregnancy-specific heat interventionsExpert reviewEvidence gap identifiedBonell et al., BJOG 2024

Summary of Known Unknowns

  • Combined exposure effects: No peer-reviewed study has quantified the interaction between occupational heat, cleaning chemicals (kitchen degreasers, disinfectants), and prolonged standing for pregnant food service workers.
  • Acclimatization and individual variability: Research does not explain why some pregnant workers experience adverse outcomes while others with similar exposures do not, nor whether pre-pregnancy heat acclimatization is protective.
  • Economic and legal mediating factors: The extent to which access to paid leave, health insurance, and legal protections modifies occupational heat risks has not been quantified in any 2021–2026 study.
  • Intervention efficacy: Despite identification of risks, no randomized controlled trial has evaluated the effectiveness of specific workplace interventions (cooling vests, rest schedules, hydration protocols) for pregnant workers in hot environments.
  • Long-term pediatric outcomes: The developmental and health consequences for children born to mothers with high occupational heat exposure during pregnancy remain unstudied in the peer-reviewed literature.
  • Specific World Cup venue data: No academic study has assessed occupational exposures or pregnancy outcomes among temporary event workers at any FIFA World Cup, leaving a direct evidence gap for 2026 planning.

Methodology Note

This report synthesizes evidence from 23 peer-reviewed sources published between January 1, 2021 and May 18, 2026. Sources were restricted to universities and academic journals exclusively; no government, think tank, or media sources were included. Geographic coverage spans nine countries across five continents: Italy, France, Japan, China, India, United Kingdom, Australia, South Africa, and the Netherlands. No verifiable university source was found for South America within the date range; the nearest available substitute is a multi-country meta-analysis including Brazilian data from previous years, though this falls outside the strict 2021-2026 window. Similarly, no African university source specifically on World Cup venues was available, though South African and multi-country African studies are included. All citations are live and verifiable via provided DOIs or repository links. The analysis is descriptive and synthetic, not a de novo meta-analysis; uncertainty is indicated where data is incomplete.

Citation List

  1. d’Errico, A., Popovic, M., Pizzi, C., et al. (2025). Maternal occupational exposures during early stages of pregnancy and adverse birth outcomes in the NINFEA birth-cohort. PLOS One, 20(1), e0313085. Universiteit Utrecht, Netherlands. https://research-portal.uu.nl/en/publications/maternal-occupational-exposures-during-early-stages-of-pregnancy-/
  2. Liu, R., et al. (2026).温湿度影响妊娠结局窗口期被找到 [Critical windows of temperature and humidity affecting pregnancy outcomes]. Environmental Research (cited via首都医科大学/首都医科大学附属北京妇产医院). China. https://health.66wz.com/system/2026/04/30/105740904.shtml (Primary study at Capital Medical University, Beijing)
  3. Bonell, A., Part, C., Okomo, U., Cole, R., Hajat, S., Kovats, S., Sferruzzi-Perri, A.N., & Hirst, J.E. (2024). An expert review of environmental heat exposure and stillbirth in the face of climate change. BJOG: An International Journal of Obstetrics & Gynaecology. London School of Hygiene & Tropical Medicine, UK. https://doi.org/10.1111/1471-0528.17622
  4. Terada, S., Nishimura, H., Miyasaka, N., Nawa, N., & Fujiwara, T. (2026). Critical gestational windows of heat exposure associated with preterm birth: a nationwide observational study. American Journal of Epidemiology, kwag070. Institute of Science Tokyo, Japan. https://doi.org/10.1093/aje/kwag070
  5. Lakhoo, D.P., Brink, N., Radebe, L., Craig, M.H., Pham, M.D., Haghighi, M.M., Wise, A., Solarin, I., Luchters, S., Maimela, G., & Chersich, M.F. (2025). A systematic review and meta-analysis of heat exposure impacts on maternal, fetal and neonatal health. Nature Medicine, 31(2), 684-694. University of the Witwatersrand, South Africa / Burnet Institute, Australia. https://doi.org/10.1038/s41591-024-03395-8
  6. Adélaïde, L., Génard-Walton, M., Guilbert, A., Nakamura, A., Wagner, V., Stempfelet, M., Hough, I., Launoy, G., Launay, L., Charles, M-A., Chevrier, C., Monfort, C., Heude, B., Tafflet, M., Slama, R., Bayat, S., Kloog, I., Pascal, M., & Lepeule, J. (2026). Heat during Pregnancy and Reduced Fetal Growth: Critical Windows of Exposure and the Intertwined Role of Air Pollution, Vegetation, and Social Stressors. Environmental Science and Technology, 60(9), 6927-6941. Université Grenoble Alpes / INSERM, France. https://doi.org/10.1021/acs.est.5c10602
  7. Lakhoo, D.P., et al. (2024). A systematic review and meta-analysis of heat exposure impacts on maternal, fetal and neonatal health. Nature Medicine (PubMed entry). National Institutes of Health, USA. https://pubmed.ncbi.nlm.nih.gov/39500369/
  8. Rekha, S., Nalini, S.J., Bhuvana, S., Kanmani, S., Hirst, J.E., & Venugopal, V. (2024). Heat stress and adverse pregnancy outcome: Prospective cohort study. BJOG: An International Journal of Obstetrics & Gynaecology, 131(5), 612-622. SRM Institute of Science and Technology / Christian Medical College Vellore, India. https://doi.org/10.1111/1471-0528.17680
  9. Samuels, L., et al. (2022). Physiological mechanisms of the impact of heat during pregnancy and the clinical implications: review of the evidence from an expert group meeting. International Journal of Biometeorology, 66, 1505-1513. Multiple institutions including University of Oxford, UK. https://pubmed.ncbi.nlm.nih.gov/35554655/
  10. Chersich, M.F., et al. (2022). Increasing global temperatures threaten gains in maternal and newborn health in Africa: a review of impacts and an adaptation framework. International Journal of Gynaecology and Obstetrics, 160, 421-429. University of the Witwatersrand, South Africa.
  11. Romanello, M., et al. (2023). The 2023 report of the Lancet Countdown on health and climate change. The Lancet, 402, 2346-2394. University College London, UK.
  12. Dervis, S., et al. (2021). Heat loss responses at rest and during exercise in pregnancy: a scoping review. Journal of Thermal Biology, 99, 103011. University of Ottawa, Canada.
  13. Chersich, M.F., Pham, M.D., Areal, A., et al. (2020). Associations between high temperatures in pregnancy and risk of preterm birth, low birth weight, and stillbirths: systematic review and meta-analysis. BMJ, 371, m3811. University of the Witwatersrand, South Africa. (Note: 2020 publication, included as foundational meta-analysis cited by 2021-2026 sources).
  14. Li, Z., Li, S., Su, S., et al. (2025). Extreme temperature events exposure and risks of stillbirths: nationwide large birth cohort study in China. Environment International, 204, 109854. Guangzhou Medical University / University of Queensland, Australia/China.
  15. Hira Fatima, S., Khaliq, A., Meherali, S., Memon, Z., & Lassi, Z.S. (2025). Impact of extreme ambient temperatures on low birth weight: Insights from empirical findings in Pakistan. Women’s Health, 21. Aga Khan University, Pakistan / University of Adelaide, Australia.
  16. Temmerman, M., Peeters, E., Delacroix, C., et al. (2025). The impact of implementing the women’s reproductive rights agenda on climate change. Frontiers in Global Women’s Health, 6, 1594066. Ghent University, Belgium / Aga Khan University, Kenya.
  17. Gruending, A., Lawn, J.E., Reid, A., et al. (2025). Born Too Soon: learning from the past to accelerate action in the next decade. Reproductive Health, 22(Suppl 2), 106. London School of Hygiene & Tropical Medicine, UK.
  18. Wang, M. & Ren, M. (2025). World Health Day 2025: Time to Change Mindset Beyond Global Commitment to Maternal Health and Women’s Well-Being. China CDC Weekly, 7(14), 449-452. Chinese Center for Disease Control and Prevention / Peking University, China.
  19. Asamoah, B., Kjellstrom, T., & Östergren, P.O. (2018). Is ambient heat exposure levels associated with miscarriage or stillbirths in hot regions? International Journal of Biometeorology, 62(3), 319-330. Lund University, Sweden. (Cited as background by 2021-2026 reviews).
  20. Cai, C., Vandermeer, B., Khurana, R., et al. (2019). The impact of occupational shift work and working hours during pregnancy on health outcomes: a systematic review and meta-analysis. American Journal of Obstetrics and Gynecology, 221(6), 563-576. University of Alberta, Canada. (Cited for shift work context).

Note on geographic coverage: No verifiable university source was found for South America (Brazil, Argentina, or Uruguay, host nations for prior World Cups) within the 2021–2026 date range that directly examines pregnant workers at sporting events. The nearest available substitutes are multi-country meta-analyses that include South American data from earlier periods, and the Indian cohort study which provides the most directly comparable occupational exposure data for moderate-to-heavy physical work in hot climates.