‘Unsurprising’: Extreme heat linked to preterm birth
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Key takeaways:
- Daily and nighttime extreme heat exposure in the third trimester is associated with increased risks for preterm birth.
- Pregnancies in greener areas were less likely to be preterm.
Extreme daily and nighttime heat exposure in the third trimester of pregnancy was linked to preterm birth in an Australian study, according to findings published in JAMA Pediatrics.
The study was prompted by an increase in frequency of extreme heat days, which is attributable to effects of climate change, according to one of the study’s authors.
“Our understanding of the relationship between heat exposure and preterm birth remains limited, and furthermore, the potential mitigating effects of green spaces or trees on heat-related preterm birth are not yet fully understood,” Shanshan Li, PhD, MD, MMed, professor of environmental change and global health at Monash University in Melbourne, told Healio.
“Our aim is to furnish compelling evidence for governments, communities, public health services, clinicians and individuals enabling them to adopt measures aimed at reducing the risks associated with preterm birth induced by heat exposure,” Li said.
Li and colleagues studied a cohort of 1,225,722 singleton live births, including 63,144 preterm births, spanning 2000 to 2020 in Sydney, Australia. They correlated birth details with community-level weather data and greenery metrics to establish a dataset for analysis.
They included levels of greenness, — or the presence of vegetation and access to green spaces that regulate temperature among other qualities — as a factor.
Compared with births that did not include heat exposure, exposure to daily extreme heat (adjusted OR = 1.61; 95% CI, 1.55-1.67) and nighttime extreme heat (aOR = 1.51; 95% CI, 1.46-1.56) in the third trimester was associated with increased risks for preterm birth.
“While it's unsurprising that heat exposure heightens the risk of preterm birth, our findings have yielded a somewhat unexpected revelation: specifically, that only heat exposure during the third trimester shows a significant association with increased risks,” Li said.
“Despite this,” Li continued, “we hold the view that heat exposure across all trimesters may indeed contribute to elevated risks of preterm birth. This intriguing nuance prompts further exploration and underscores the complexity of the relationship between heat exposure and prenatal outcomes.”
Li said the study highlighted the role that health care providers play in counseling pregnant women to avoid excessive heat exposure, especially during the third trimester, to mitigate the risk for preterm birth and underscored the urgency for governments and communities to prioritize the expansion of green spaces by planting more trees and grasslands.
“We would like to see some studies that can extend the scope of this study globally, delving deeper into the economic ramifications linked with heat exposure and exploring effective strategies to alleviate this burden,” Li said. “By broadening our investigation, we aspire to offer insights that can inform policy decisions and interventions aimed at safeguarding public health and promoting resilience in the face of climate-related challenges.”
In an accompanying editorial, Heather H. Burris, MD, MPH, a neonatologist at The Children’s Hospital of Philadelphia, and Allan C. Just, PhD, an associate professor of epidemiology at the Brown University School of Public Health, wrote that the “next step” involves analyzing “the real-world impact of interventions such as urban greening and tree-planning initiatives to mitigate climate change impacts for maximal health benefit.”
“It is becoming increasingly apparent that extreme heat is harmful for human health, including during pregnancy,” they wrote. “Such data and studies are crucial to inform public health efforts to optimize health across the life span.”
References:
Burris HH, et al. JAMA Pediatr. 2024;doi:10.1001/jamapediatrics.2024.0008.
Ye T, et al. JAMA Pediatr. 2024;doi:10.1001/jamapediatrics.2024.0001.
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