Study says wildfire smoke exposure in pregnancy may raise risk of preterm birth Photograph.

STORY HIGHLIGHTS

To assess the daily amounts of wildfire smoke in the participants’ ZIP codes during their pregnancies, the researchers first collected data from hospital records of pregnant women from 2007 to 2012. The results suggested that just one day of exposure to smoke moderately raised the risk of spontaneous preterm birth — medically defined as before the 37th week of pregnancy.  

Those exposed to wildfire smoke for at least one day have a higher chance of giving birth prematurely, according to a study of more than 2.5 million women who are pregnant in California. The results, which are still undergoing peer review, were presented on Saturday at the annual conference of the Society for Maternal-Fetal Medicine, and would be published in the American Journal of Obstetrics and Gynecology.

To assess the daily amounts of wildfire smoke in the participants’ ZIP codes during their pregnancies, the researchers first collected data from hospital records of pregnant women from 2007 to 2012.

The results suggested that just one day of exposure to smoke moderately raised the risk of spontaneous preterm birth — medically defined as before the 37th week of pregnancy. 

“Most pregnant persons are having well over one day of exposure, and the chronicity of this exposure, which continues to increase, is really the worrisome relationship with wildfire smoke,” said Dr Anne Waldrop, the study’s lead author and a maternal-fetal medicine fellow at Stanford University told NBC news. 

During their first or second trimesters, or the four weeks preceding conception, 86 per cent of the pregnant women tested in California, according to Waldrop’s research, had been exposed to fine particulate matter from wildfire smoke. Over the course of that period, the research subjects were exposed to smoke on average for more than seven days.

Only preterm births occurring within the first 20 weeks of pregnancy were linked to exposure; preconception exposure was not.

Another study discovered that air pollution likely caused roughly six million preterm births globally in 2019. According to Rakesh Ghosh, an epidemiologist at the University of California, San Francisco, and the author of that paper, who spoke to NBC news, inhaling smoke from wildfires during the first trimester may cause the amniotic sac to rupture early as a result of inflammation.