Risk of cardiovascular events during labor and delivery associated with acute ambient temperature changes

Purpose: We assessed acute risk of cardiovascular events at labor/delivery with exposure to ambient temperatures during the week prior to delivery in a low-risk population. Methods: A case-crossover design evaluated 191 women with cardiovascular events at labor/delivery in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Consecutive Pregnancies Study (Utah, 2002–2010). Using conditional logistic regression models, we estimated the odds ratio (OR) and 95% confidence interval (CI) for each 1 °Celsius (1.8°F) increase in the warm season (May-October) or decrease in the cold season (November-April) in the week prior to delivery compared to two weeks prior and after delivery. Results: Cardiovascular events during delivery included acute myocardial infarction (n = 1), stroke (n = 29), heart failure (n = 7), cardiac arrest (n = 118), and unspecified (n = 39). Cardiovascular event risk increased by 9% (95% CI: 1.02, 1.18) for every 1 °C increase in average temperature in the week prior to delivery during the warm season and increased 6% (95% CI: 1.00, 1.13) for every 1 °C decrease during the cold season. Conclusion: Acute temperature changes in the week prior to delivery were associated with increased risk of cardiovascular events at labor/delivery.