Heat Exposure and Preterm Birth in Sub-Saharan Africa: An Individual Participant Data Meta-Analysis
1
Wits Planetary Health Research, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
2
Centre for Sexual Health and HIV/AIDS Research, Harare, Zimbabwe
3
Place Alert Labs, Department of Surveying and Geomatics, Faculty of the Built Environment, Midlands State University, Gweru, Zimbabwe
4
Climate System Analysis Group, University of Cape Town, Cape Town, South Africa
5
University Peleforo Gon Coulibaly, Korhogo, Côte dIvoire
6
Discipline of Public Health and Primary Care, Institute of Population Health, School of Medicine, Trinity College Dublin, Dublin, Ireland
7
Trinity College Dublin, Dublin, Ireland
8
IBM Research Africa, Johannesburg, South Africa
9
Liverpool School of Tropical Medicine, Liverpool, United Kingdom
10
Department of Public Health and Primary Care, Ghent University, Ghent, Belgium
Popul. Med. 2026;8(Supplement Supplement 1):A432
ABSTRACT
ABSTRACT:
Preterm birth is the leading cause of child morbidity and mortality and has been consistently associated with heat exposure. However, most evidence comes from high-income settings. This study aimed to quantify the effects of short-term heat exposure on preterm birth across sub-Saharan Africa, where heat-related vulnerabilities are highest.
METHODS:
We conducted an individual participant data (IPD) meta-analysis of clinical trials and cohorts conducted in sub-Saharan Africa (2000–2022). Eligible datasets were cleaned, geolocated, harmonised, and linked to ERA5 temperature data. A two-stage random-effects meta-analysis design was applied; each study was analysed separately using time-stratified case-crossover designs then, study-specific estimates were pooled. Effect modification by urbanicity and climate zones was explored.
RESULTS:
We included 7 studies comprising 27217 singleton births, with MomCare Project (Kenya) contributing 41.7% (n=11341), followed by The Safe Passage Study (South Africa) (23.9%; n=6485) and PREGACT (multi-country) (12.1%; n=3304). Overall, 4622 births (17.0%) were preterm, ranging from 4.85% in STOPMIP (Kenya) to 24.7% in MomCare Project (Kenya). In pooled analyses, compared with the 75th percentile of temperature, exposure at the 90th percentile in the week before birth was associated with an 8% increase in the odds of preterm birth (OR=1.08; 95% CI: 0.93 – 1.26; I²=16.7%). All studies showed a harmful direction of effect, with the largest effect (OR=1.36; 95% CI: 0.35-5.33) in STOPMIP, however, none were statistically significant. Meta-regression suggested a threshold-type exposure–response, with increasing risk above 21°C, with stronger effects in rural areas compared to urban and arid and tropical climate zones compared to temperate climate zones.
CONCLUSIONS:
Short-term heat exposure may increase the risk of preterm birth in sub-Saharan Africa. As global warming intensifies, integrating pregnant women and newborns into heat-adaptation planning, early warning systems, and public-health surveillance is urgently needed, particularly in low- and middle-income countries with the highest vulnerability to heat-related health impacts.
Preterm birth is the leading cause of child morbidity and mortality and has been consistently associated with heat exposure. However, most evidence comes from high-income settings. This study aimed to quantify the effects of short-term heat exposure on preterm birth across sub-Saharan Africa, where heat-related vulnerabilities are highest.
METHODS:
We conducted an individual participant data (IPD) meta-analysis of clinical trials and cohorts conducted in sub-Saharan Africa (2000–2022). Eligible datasets were cleaned, geolocated, harmonised, and linked to ERA5 temperature data. A two-stage random-effects meta-analysis design was applied; each study was analysed separately using time-stratified case-crossover designs then, study-specific estimates were pooled. Effect modification by urbanicity and climate zones was explored.
RESULTS:
We included 7 studies comprising 27217 singleton births, with MomCare Project (Kenya) contributing 41.7% (n=11341), followed by The Safe Passage Study (South Africa) (23.9%; n=6485) and PREGACT (multi-country) (12.1%; n=3304). Overall, 4622 births (17.0%) were preterm, ranging from 4.85% in STOPMIP (Kenya) to 24.7% in MomCare Project (Kenya). In pooled analyses, compared with the 75th percentile of temperature, exposure at the 90th percentile in the week before birth was associated with an 8% increase in the odds of preterm birth (OR=1.08; 95% CI: 0.93 – 1.26; I²=16.7%). All studies showed a harmful direction of effect, with the largest effect (OR=1.36; 95% CI: 0.35-5.33) in STOPMIP, however, none were statistically significant. Meta-regression suggested a threshold-type exposure–response, with increasing risk above 21°C, with stronger effects in rural areas compared to urban and arid and tropical climate zones compared to temperate climate zones.
CONCLUSIONS:
Short-term heat exposure may increase the risk of preterm birth in sub-Saharan Africa. As global warming intensifies, integrating pregnant women and newborns into heat-adaptation planning, early warning systems, and public-health surveillance is urgently needed, particularly in low- and middle-income countries with the highest vulnerability to heat-related health impacts.
| eISSN: | 2654-1459 |
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