Ambient temperature plays a crucial role in hypertensive disorders in pregnancy, especially preeclampsia or eclampsia, with bidirectional effects in different pregnancy trimesters.

Hypertensive disorders in pregnancy (HDP) pose a significant threat to maternal well-being and are a leading cause of maternal mortality. Recent research has suggested that pregnant women are particularly susceptible to the impact of ambient temperature, although findings on its association with HDP have been inconclusive. Hence, this systematic review and meta-analysis investigated whether exposure to extreme temperatures is linked to a modified risk of developing HDP.

Investigators conducted a thorough search of the PubMed, Web of Science, EMBASE, and the Cochrane Library databases. The inclusion criteria comprised cohort or case-control studies examining the correlation between extreme temperature exposure either prior to or during pregnancy and the occurrence of HDP. Heat sources like saunas and hot baths were excluded from the analysis. The odds ratios (OR) were pooled to examine the connection between extreme temperature exposure and the development of eclampsia or preeclampsia.

The analysis incorporated 15 studies encompassing 4,481,888 subjects, with five studies encompassed in the meta-analysis. The overall findings indicated that during the first half of pregnancy, exposure to heat heightened the danger of developing preeclampsia, eclampsia, and gestational hypertension, while exposure to cold minimized the risk. Specifically, the meta-analysis illustrated that in the first half of pregnancy, heat exposure escalated the chances of preeclampsia or eclampsia (OR 1.54, 95% confidence interval [CI]: 1.10, 2.15), whereas cold exposure curtailed the risk (OR 0.90, 95% CI: 0.84, 0.97).

Ambient temperature emerges as a crucial factor influencing HDP onset, particularly in the context of preeclampsia or eclampsia. The impact of extreme temperatures appears to vary bidirectionally across different trimesters of pregnancy, necessitating further investigation by future studies. Maintaining appropriate ambient temperatures is crucial for pregnant women to mitigate the potential risks of developing HDP.