T h e i m p a c t s of excessive heat on p r e t e r m labor

Transcription

1 HOT AS BLUE BLAZES: T h e i m p a c t s of excessive heat on p r e t e r m labor ASHLEY WARD, PHD CLIMATE INTE GRATIO N AND OUTR EACH ASSOCIATE C ISA DEPARTMENT OF GEOGRAPHY UNIV ERSITY OF NORTH CAROLINA AT CAHPEL HILL

2 Heat-Related Illness R a t e s by Zip Code, NC Kovach, M., Konrad, C., Fuhrmann, C. (2015). Area-level risk factors for heat-related illness in rural and urban locations across North Carolina, USA. Applied Geography. 60,

3 Percent of Preterm Births of top 10 are in the Southeas t Al l of s outheas t with exception of V irginia in top 20 & exceed national average for preterm births

4 Associations with P r e t e r m Bir th in NC Hi st or y of pr et er m bi r t h Multiple births Smoking, alcohol, or drug use Late or no prenatal care Diabetes or hypertens ion Infection S ources : 1 ) B orn too s oon and too s mall in North C arolina. M arch of D imes F oundation, M arch 2015 ; 2 ) B erkowitz, G S, P apiernick E E pidemiology of preterm birth. E pidemiological R eview 15 ( 2 ) :

5 P r e t e r m Birth R a t e s by Zip Code, NC

6 Previous work onexcessive heat impacts to pregnant women Focuses on single events Exami nes i mpact of al l t emperat ure ext remes Western United States or overs eas Findings: 1.Heat waves associated with pre-term birth but how much depends upon strength and length of exposure 2. Impacts range from <1% 2% increase in risk for each increase in degree interval (most common association with heat index) 3. Heat Index highly correlated

7 A im s 1. Describe t he relat ionship between excessive heat days and pret erm delivery (<37 weeks ) in NC, Max temp - Min temp - Mean temp - Heat index day lags for each - 3 day cumulative for each - departure f rom normal 2. Determine thres holds at whic h health impac ts occur for each meteorolog ical variable

8 Methods 1. Population: al l live, singleton births in NC during heat seasons (May- September) 2. Exposure: P RISM data was provided for each available variable; other variables calculated f rom thes e provided variables (heat index, mean temperature, lags, and cumulative variables ) 3. Outcome clas si f ication: b i r t h certificate data from NC Vi tal Records was obtained 4. Other variables : maternal age, maternal race, maternal ethnicity, principal source of payment, access to OB/ midwife, birth weight, region, urban acces s ( determined from C ensus)

9 M ethods S tatis tic al Analys is: - Case- cros sover study with t ime- stratified referent selection - Cox Proportional Hazards Descr iptive Statis tic s: - Individual and county- level summaries of pre- term b i r t h Binomial Generalized Additive Model: - To establis h thres holds at which impacts are experienced

10 Summary Statistics: Preterm birth, NC

11 Results Statistically significant associations: Max temp Min temp* Mean temp 3 day cumulative for each No significant differences in race, slight differences by region Threshold: two degree temperature groups of analysis Odds Ratio: increased percent in odds of preterm birth associated with temperature threshold (upper and lower confidence interval ranges at 95% confidence interval Percentile: placement of respective threshold temperature among regional distribution of temperature

12 Where to go from here? Heat Early Warning S ystem Unders tanding changes in r is k Engaging with pregnant women to unders tand contextual factors around r is k

13 Suggested thresholds for warnings Yel low: temperatures at which any impact to preterm b i r t h is detected Red : t em p er at ur es i n t he 90t h p er cen t i l e w i t h n o t ab l y h i gh er i m p act s t o p r et er m b i r t h

14 Where to go from here? Heat Early Warning S ystem Unders tanding changes in r is k Engaging with pregnant women to unders tand contextual factors around r is k

15 *Stations queried: Asheville, NC; Hickory, NC Note: Asheville, NC d i d not register any events at t h r e s h o l d t e m p e r a t u r e s

16 *Stations queried: Raleigh, NC; G r e e n s b o r o, NC

17 * S t a t i o n s q u e r i e d : Fayetteville, N C L o w t h r e s h o l d f r e q u e n c y v e r y h i g h th is g r a p h r e p r e s e n t s t h e p o i n t o f 4% o r g r e a t e r i n c r e a s e i n o d d s of p r e t e r m labor

18 Where to go from here? Heat Early Warning S ystem Unders tanding changes in r is k Engaging with pregnant women to unders tand contextual factors around r is k

19 Special thanks Co-Authors Charles Konrad, Director, Southeast Regional Climate Center; Professor, Department of Geography, University of North Carolina at Chapel Hill Jordan Clark, PhD Candidate, Department of Geography, University of North Carolina at Chapel Hill Rachel Woodul, PhD Candidate, Department of Geography, University of North Carolina at Chapel Hill Jordan McCleod, Climatologist, Southeast Regional Climate Center