Associations between extreme temperature exposure and hypertensive disorders of pregnancy: A systematic review and meta-analysis.
BACKGROUND Evidence linking extreme temperature exposure to hypertensive disorders of pregnancy (HDP) remains inconsistent, with limited synthesis on exposure timing and climatic vulnerability. OBJECTIVE To quantify associations of extreme heat, cold, and season-related exposures with HDP, preeclampsia (PE), and gestational hypertension (GH), and to identify critical windows and vulnerable climate zones. METHODS We systematically searched five databases up to February 2026. Observational studies (≥500 participants) reporting HDP outcomes with recognized diagnostic criteria were included. Random-effects meta-analyses were performed with subgroup analyses by exposure window, climate zone, and study period. RESULTS Twenty-eight studies (23,268,235 participants) were included. Heat exposure was significantly associated with increased HDP risk (pooled OR = 1.58, 95% CI: 1.31-1.90; I² = 98%), particularly for PE (OR = 2.01, 95% CI: 1.42-2.84; I² = 99%). Cold exposure showed no statistically significant pooled association. Stronger associations were observed in arid climates (PE: OR = 2.09, 95% CI: 1.19-3.66; I² = 40%) and during late gestation (≥28 weeks: OR = 1.23, 95% CI: 1.05-1.45; I² = 95%). Continuous temperature modeling revealed a linear exposure-response relationship (OR per 1 °C = 1.03, 95% CI: 1.02-1.04; I² = 48%). CONCLUSION Maternal heat exposure is significantly associated with increased HDP risk, particularly preeclampsia, with pronounced effects in arid regions and late pregnancy. These findings support integrating climate-adaptive strategies into antenatal care.