Impacts of heat and wildfire on preterm birth

Sandie Ha; John T Abatzoglou; Adeyemi Adebiyi; Sneha Ghimire; Valerie Martinez; Meng Wang; Rupa Basu

doi:10.1016/j.envres.2024.119094

Impacts of heat and wildfire on preterm birth

Environ Res. 2024 Jul 1;252(Pt 4):119094. doi: 10.1016/j.envres.2024.119094. Epub 2024 May 7.

Authors

Sandie Ha¹, John T Abatzoglou², Adeyemi Adebiyi³, Sneha Ghimire⁴, Valerie Martinez⁴, Meng Wang⁵, Rupa Basu⁶

Affiliations

¹ Department of Public Health, School of Social Sciences, Humanities and Arts, Health Science Research Institute, University of California, 5200 N Lake Rd, 95343, Merced, CA, USA. Electronic address: Sha55@ucmerced.edu.
² Department of Management of Complex Systems, School of Engineering, University of California, Merced, USA.
³ Department of Life and Environmental Sciences, School of Natural Sciences, University of California, Merced, USA.
⁴ Department of Public Health, School of Social Sciences, Humanities and Arts, Health Science Research Institute, University of California, 5200 N Lake Rd, 95343, Merced, CA, USA.
⁵ Department of Epidemiology and Environmental Health, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, USA.
⁶ Air and Climate Epidemiology Section, Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, Oakland, CA, USA.

PMID: 38723988
DOI: 10.1016/j.envres.2024.119094

Abstract

Background: Climate change continues to increase the frequency, intensity, and duration of heat events and wildfires, both of which are associated with adverse pregnancy outcomes. Few studies simultaneously evaluated exposures to these increasingly common exposures.

Objectives: We investigated the relationship between exposure to heat and wildfire smoke and preterm birth (PTB).

Methods: In this time-stratified case-crossover study, participants consisted of 85,806 California singleton PTBs (20-36 gestational weeks) from May through October of 2015-2019. Birthing parent ZIP codes were linked to high-resolution daily weather, PM_2.5 from wildfire smoke, and ambient air pollution data. Heat day was defined as a day with apparent temperature >98th percentile within each ZIP code and heat wave was defined as ≥2 consecutive heat days. Wildfire-smoke day was defined as a day with any exposure to wildfire-smoke PM_2.5. Conditional logistic regression was used to calculate the odds ratio (OR) and 95% confidence intervals (CI) comparing exposures during a hazard period (lags 0-6) compared to control periods. Analyses were adjusted for relative humidity, fine particles, and ozone.

Results: Wildfire-smoke days were associated with 3.0% increased odds of PTB (OR_lag0: 1.03, CI: 1.00-1.05). Compared with white participants, associations appeared stronger among Black, Hispanic, Asian, and American Indians/Alaskan Native participants. Heatwave days (OR_lag2: 1.07, CI: 1.02-1.13) were positively associated with PTB, with stronger associations among those simultaneously exposed to wildfire smoke days (OR_lag2: 1.19, CI: 1.11-1.27). Similar findings were observed for heat days and when other temperature metrics (e.g., maximum, minimum) were used.

Discussion: Heat and wildfire increased PTB risk with evidence of synergism. As the occurrence and co-occurrence of these events increase, exposure reduction among pregnant people is critical, especially among racial/ethnic minorities.

Keywords: Climate change; Heat; Pregnancy; Preterm birth; Smoke; Wildfires.

MeSH terms

Adult
Air Pollutants / analysis
California / epidemiology
Cross-Over Studies*
Female
Hot Temperature* / adverse effects
Humans
Particulate Matter / analysis
Pregnancy
Premature Birth* / epidemiology
Smoke / adverse effects
Wildfires*
Young Adult

Substances

Smoke
Air Pollutants
Particulate Matter