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.