These births occurred before 37 weeks of pregnancy when incomplete development increases the risk of various neurodevelopmental, gastrointestinal and respiratory complications, and even death.
‘Wildfire smoke exposure during pregnancy can increase the preterm birth risk.’
Wildfire smoke contains high levels of the smallest and deadliest type of particle pollution, known as PM 2.5.These specks of toxic soot, or particulate matter, are so fine they can embed deep in the lungs and pass into the bloodstream, just like the oxygen molecules we need to survive.
This research started as massive wildfires are again blazing through parched landscapes in the western U.S. Just a year after a historic wildfire season torched more than 4 million acres of California and produced some of the worst daily air pollution ever recorded in the state.
Researchers stated one possible explanation for the link between wildfire smoke exposure and preterm birth is that the pollution may trigger an inflammatory response that sets delivery in motion.
“In the future, we expect to see more frequent and intense exposure to wildfire smoke throughout the West due to a confluence of factors, including climate change, a century of fire suppression and construction of more homes along the fire-prone fringes of forests, scrublands and grasslands. As a result, the health burden from smoke exposure – including preterm births – is likely to increase,” said lead author Sam Heft-Neal, a research scholar at Stanford’s Center on Food Security and the Environment.
After accounting for other factors known to influence preterm birth risk, such as temperature, baseline pollution exposure and the mother’s age, income, race or ethnic background.
They investigated patterns of preterm birth within changed in different areas when the number and intensity of smoke days rose above normal for that location.
They found that every additional day of smoke exposure during pregnancy raised the risk of preterm birth, regardless of race, ethnicity or income. A full week of exposure translated to a 3.4 percent greater risk relative to a mother exposed to no wildfire smoke.
Exposure to intense smoke during the second trimester between 14 and 26 weeks of pregnancy had the strongest impact, especially when smoke contributed more than 5 additional micrograms per cubic meter to daily PM 2.5 concentrations.
While as a society it will be extremely difficult to fully eliminate all pollutants from the air but reductions in key pollutants below current acceptable levels could be beneficial for public health.