High ambient temperatures and hypertensive disorders of pregnancy: a systematic review
Abstract
Introduction: Exposure to high ambient temperatures (heat), is consistently associated with adverse birth outcomes, particularly preterm birth, however, evidence for maternal outcomes, including hypertensive disorders of pregnancy (HDP), remains unclear. HDP are a leading cause of maternal mortality and morbidity, whose aetiology is poorly understood. In the context of climate change, clarifying this potential association is of global health importance.
Methods: We searched PubMed, EMBASE and Web of Science (inception to 23rd September 2025), for studies examining associations between heat and HDP (gestational hypertension, pre-eclampsia and eclampsia). Two reviewers independently screened, extracted data and assessed risk of bias. A narrative synthesis was completed.
Results: Thirty-six studies (14 cohort, 1 case-control and 21 ecological time-series; published 1965-2025) from 3,503 records screened. Together, these included over 8.3 million pregnancies, 86,065 cases of gestational hypertension/any HDP, 190,587 cases of pre-eclampsia and 2,218 cases of eclampsia, across 18 countries. Ten cohorts reported increased HDP risk associated with heat in early-pregnancy. However, three reported non-significant associations and one a protective association, possibly reflecting insufficient power, inappropriate exposure windows, or poor preservation of temporality. Ecological results were heterogeneous, potentially reflecting variation in exposure windows examined (e.g., month of delivery, diagnosis, hospitalisation, or conception). Eight reported increased risk, five reduced, five non-significant, and three didn’t conduct statistical testing.
Conclusions: Cohort evidence, largely from the past decade, suggest early-pregnancy heat exposure may increase HDP risk. However, more high-quality, individual-level studies in representative populations in different climate zones are needed to clarify this association which has implications for climate action efforts.
Key messages: • Heat exposure in early pregnancy may increase HDP risk.
• Further methodologically rigorous, geographically diverse cohort studies are needed to clarify this association.
Related
- Ambient temperature exposure and hypertensive disorders of pregnancy in Sweden
- A systematic review of the influence of hypertensive disorders of pregnancy on the mental health of expectant mothers in Nigeria
- Kidney Outcomes in Offspring Exposed to Hypertensive Disorders of Pregnancy: A Systematic Review and Meta-Analysis
- Hypertension in People with Multiple Sclerosis: Epidemiology, Mechanisms, Hypertensive Disorders of Pregnancy, and Clinical Implications.
- Causal effects of physical activity and sedentary behaviors on hypertensive disorders of pregnancy: a two-sample Mendelian randomization study
BibTeX
@article{brennan2026high,
title = {{High ambient temperatures and hypertensive disorders of pregnancy: a systematic review}},
author = {MM Brennan and T O’Dowd and NB Brink and D Travill and C Dumbura and C Devantier-Du Pleiss and L Radebe and ND McCarthy and MF Chersich and D Lakhoo},
journal = {The European Journal of Public Health},
year = {2026},
month = oct,
doi = {10.1093/eurpub/ckag169.277},
url = {https://doi.org/10.1093/eurpub/ckag169.277},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - High ambient temperatures and hypertensive disorders of pregnancy: a systematic review
AU - MM Brennan
AU - T O’Dowd
AU - NB Brink
AU - D Travill
AU - C Dumbura
AU - C Devantier-Du Pleiss
AU - L Radebe
AU - ND McCarthy
AU - MF Chersich
AU - D Lakhoo
PY - 2026
DA - 2026/10/01
JO - The European Journal of Public Health
DO - 10.1093/eurpub/ckag169.277
UR - https://doi.org/10.1093/eurpub/ckag169.277
AB - Introduction: Exposure to high ambient temperatures (heat), is consistently associated with adverse birth outcomes, particularly preterm birth, however, evidence for maternal outcomes, including hypertensive disorders of pregnancy (HDP), remains unclear. HDP are a leading cause of maternal mortality and morbidity, whose aetiology is poorly understood. In the context of climate change, clarifying this potential association is of global health importance. Methods: We searched PubMed, EMBASE and Web of Science (inception to 23rd September 2025), for studies examining associations between heat and HDP (gestational hypertension, pre-eclampsia and eclampsia). Two reviewers independently screened, extracted data and assessed risk of bias. A narrative synthesis was completed. Results: Thirty-six studies (14 cohort, 1 case-control and 21 ecological time-series; published 1965-2025) from 3,503 records screened. Together, these included over 8.3 million pregnancies, 86,065 cases of gestational hypertension/any HDP, 190,587 cases of pre-eclampsia and 2,218 cases of eclampsia, across 18 countries. Ten cohorts reported increased HDP risk associated with heat in early-pregnancy. However, three reported non-significant associations and one a protective association, possibly reflecting insufficient power, inappropriate exposure windows, or poor preservation of temporality. Ecological results were heterogeneous, potentially reflecting variation in exposure windows examined (e.g., month of delivery, diagnosis, hospitalisation, or conception). Eight reported increased risk, five reduced, five non-significant, and three didn’t conduct statistical testing. Conclusions: Cohort evidence, largely from the past decade, suggest early-pregnancy heat exposure may increase HDP risk. However, more high-quality, individual-level studies in representative populations in different climate zones are needed to clarify this association which has implications for climate action efforts. Key messages: • Heat exposure in early pregnancy may increase HDP risk. • Further methodologically rigorous, geographically diverse cohort studies are needed to clarify this association.
SN - 1101-1262
SN - 1464-360X
ER -