Short-term heat exposure and cumulative adverse pregnancy outcomes among women living with HIV in Johannesburg, South Africa
1
Wits Planetary Health, Johannesburg, South Africa
2
Paediatrics, University of the Witwatersrand Faculty of Health Sciences, Johannesburg, South Africa
3
Public Health and Primary Care, Trinity College Dublin, Dublin, Ireland
4
Empilweni Services and Research Unit, Rahima Moosa Mother and Child Hospital, University of the Witwatersrand, Johannesburg, South Africa
Popul. Med. 2026;8(Supplement Supplement 1):
ABSTRACT
BACKGROUND:
Rising ambient temperatures increase risks to maternal and neonatal health, yet it remains unclear whether chronic conditions, particularly maternal HIV infection, modify susceptibility to heat-related adverse pregnancy outcomes (APOs). In high HIV-burden settings, women living with HIV (WLHIV) have elevated baseline risks of APOs that may be amplified by short-term heat exposure. This study examined the short-term effects of heat exposure on APOs and assessed effect modification by maternal HIV status.
METHODS:
A time-stratified case-crossover study was conducted using data from the Ubomi Buhle Pregnancy Exposure Registry at a tertiary hospital in Johannesburg, South Africa, between January 2021 and September 2025. Short-term ambient temperature exposure in the week preceding delivery was linked to APOs at the facility level using ERA5 reanalysis data at a 0.25° × 0.25° spatial resolution and analysed using distributed lag non-linear models. Associations were examined for individual APOs and a composite adverse outcome capturing cumulative vulnerability, with analyses stratified by maternal HIV status and supported by extensive sensitivity analyses.
RESULTS:
WLHIV accounted for 18.1% of deliveries. In the overall cohort and among HIV-negative women, associations between high ambient temperature and APOs were inconsistent and non-significant. In contrast, among WLHIV, short-term exposure to elevated ambient temperatures was associated with increased odds of APOs, with the strongest associations observed for the composite outcome (OR 1.57, 95% CI 1.01–2.45). This association remained robust across multiple sensitivity analyses. Individual APOs among WLHIV showed suggestive but non-significant associations.
CONCLUSIONS:
Short-term heat exposure was associated with increased odds of APOs among WLHIV, relative to HIV-negative women exposed to similar temperatures. These findings suggest that heat acts as a stressor that modifies existing biological vulnerability in HIV-affected pregnancies. As global temperatures continue to rise, targeted heat adaptation strategies for WLHIV may be critical to protecting maternal and neonatal health in high-burden settings.
Rising ambient temperatures increase risks to maternal and neonatal health, yet it remains unclear whether chronic conditions, particularly maternal HIV infection, modify susceptibility to heat-related adverse pregnancy outcomes (APOs). In high HIV-burden settings, women living with HIV (WLHIV) have elevated baseline risks of APOs that may be amplified by short-term heat exposure. This study examined the short-term effects of heat exposure on APOs and assessed effect modification by maternal HIV status.
METHODS:
A time-stratified case-crossover study was conducted using data from the Ubomi Buhle Pregnancy Exposure Registry at a tertiary hospital in Johannesburg, South Africa, between January 2021 and September 2025. Short-term ambient temperature exposure in the week preceding delivery was linked to APOs at the facility level using ERA5 reanalysis data at a 0.25° × 0.25° spatial resolution and analysed using distributed lag non-linear models. Associations were examined for individual APOs and a composite adverse outcome capturing cumulative vulnerability, with analyses stratified by maternal HIV status and supported by extensive sensitivity analyses.
RESULTS:
WLHIV accounted for 18.1% of deliveries. In the overall cohort and among HIV-negative women, associations between high ambient temperature and APOs were inconsistent and non-significant. In contrast, among WLHIV, short-term exposure to elevated ambient temperatures was associated with increased odds of APOs, with the strongest associations observed for the composite outcome (OR 1.57, 95% CI 1.01–2.45). This association remained robust across multiple sensitivity analyses. Individual APOs among WLHIV showed suggestive but non-significant associations.
CONCLUSIONS:
Short-term heat exposure was associated with increased odds of APOs among WLHIV, relative to HIV-negative women exposed to similar temperatures. These findings suggest that heat acts as a stressor that modifies existing biological vulnerability in HIV-affected pregnancies. As global temperatures continue to rise, targeted heat adaptation strategies for WLHIV may be critical to protecting maternal and neonatal health in high-burden settings.
| eISSN: | 2654-1459 |
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