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Updated: Feb 22, 2026

Esophageal Heat Transfer for Patient Temperature Control and Targeted Temperature Management
Published on: November 21, 2017
Ambient temperature and risk of cardiovascular events at labor and delivery: A case-crossover study
Sandie Ha1, Kelly Nguyen2, Danping Liu3
1Epidemiology Branch, Division of Intramural Population Health Research, NICHD, 6710B Rockledge Drive Room 3119, MSC 7004 Bethesda, Rockville, MD, USA; School of Social Sciences, Humanties and Arts, University of California, Merced, CA, USA.
Background:
Extreme ambient temperatures are linked to cardiac events in the general population, but this relationship is unclear among pregnant women. We estimated the associations and attributable risk between ambient temperature and the risk of cardiovascular event at labor/delivery, and investigated whether these associations vary by maternal race/ethnicity.
Methods:
We identified 680 women with singleton deliveries affected by cardiovascular events across 12 US sites (2002-2008). Average daily temperature during the week before, delivery day, and each of the seven days before delivery was estimated for each woman. In a case-crossover analysis, exposures during these hazard periods were compared to two control periods before and after delivery using conditional logistic regression adjusted for other environmental factors.
Results:
During the cold season (October-April), 1°C lower during the week prior to delivery was associated with a 4% (95% CI: 1-7%) increased risk of having a labor/delivery affected by cardiovascular events including cardiac arrest and stroke. During the warm season (May-September), 1°C higher during the week prior was associated with a 7% (95% CI: 3-12%) increased risk. These risks translated to 13.4 and 23.9 excess events per 100,000 singleton deliveries during the cold and warm season, respectively. During the warm season, the risks were more pronounced on days closer to delivery and Black women appeared to be more susceptible to the same temperature increase.
Conclusion:
Small changes in temperature appear to affect the risk of having cardiovascular events at labor/delivery. Black women had a differentially higher warm season risk. These findings merit further investigation.
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