The Impact of Excessive Heat on Preterm Birth, North Carolina, 2011−15

Research on the impact of excessive heat on pregnant women has focused largely on outcomes following extreme events, such as particular heat waves, or on the impact of all temperature extremes (heat and cold weather) on pregnant women. Consistently the literature has shown a statistically significant relationship between excessive heat with pre-term birth with studies concentrated largely in the western states of the U.S. or other nations. The association between excessive heat and pre-term birth has not been examined in the Southeastern US where maternal outcomes are some of the most challenging in the nation. Unlike previous studies that focus on the impacts of a single heat wave event, this study seeks to understand the impact of chronic high heat over a 5-year period during the heat season of May-September, 2011-2015. To achieve this goal, a case-crossover study design is employed to understand differences between the impact of excessive heat on preterm birth as well as regional difference in these outcomes in NC. Temperature thresholds for impacts are also established. The results reveal significant impacts to pregnant women exposed to excessive heat with regional variations. The results of this work are part of a collaboration between NOAA’s Carolina’s RISA and the Southeast Regional Climate Center to identify vulnerabilities to heat related illness in NC and establish prevention measures, such as early warning systems, to offset the impact of heat.