Vol. 120, No. 9 News | Science SelectionsOpen AccessFollowup in Southern California: Decreased Birth Weight following Prenatal Wildfire Smoke Exposureis accompanied byBirth Weight following Pregnancy during the 2003 Southern California Wildfires Rebecca Kessler Rebecca Kessler Search for more papers by this author Published:1 September 2012https://doi.org/10.1289/ehp.120-a362bCited by:1AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit In fall 2003 wildfires blazed in Southern California, sending pollutant-laden smoke directly into the heavily populated Los Angeles and Orange counties. A new study of birth records from the area shows a decreased average birth weight among infants carried in utero during the wildfires [EHP 120(9):1340–1345; Holstius et al.].Chronic maternal exposure to ambient particulate matter (PM) and indoor biomass smoke during pregnancy has been linked to decreased infant birth weight, although similar effects attributable to wildfire smoke have been little studied. In this study, researchers analyzed 886,034 birth records of babies delivered between 2001 and 2005 in the South Coast Air Basin, an area that overlaps the wildfire-affected regions. They compared the average birth weight of infants carried in utero during the wildfires with that of infants who were either born before or conceived after the wildfires. They also compared birth weights of infants exposed during the first, second, and third trimesters of pregnancy.After adjusting for infant sex, gestational age at birth, and other factors known to influence birth weight, the researchers found that exposed infants weighed an average of 6.1 g (0.2 oz) less at birth than unexposed infants. Infants exposed during the second trimester showed the largest average reduction, at 9.7 g. Infants exposed during the third trimester showed an average reduction of 7.0 g, and those exposed during the first trimester showed an average reduction of 3.3 g (the latter was not statistically significant). The trends were corroborated by a sensitivity analysis that compared pregnant mothers according to whether the air-pollution monitor nearest their residence recorded high or low PM levels during the wildfires.Smoke from wildfires burning across Southern California, 27 October 2003AP Photo/Kevork DjansezianThe small reductions in birth weight attributed to the wildfires are unlikely to have serious health effects in any given individual. However, wildfires are predicted to increase in frequency and severity as climate change progresses, and the researchers note that the proportion of low-birth-weight babies—those weighing less than 2,500 g (5.5 lb) at birth—could rise as a result. This could have important populationwide repercussions because these babies are at increased risk for a variety of poor health outcomes.PM and carbon monoxide are among pollutants released by wildfires that could plausibly contribute to the birth-weight decrease. However, the researchers note that other pathways are possible and worthy of investigation, among them the increased stress that living through a wildfire may place on pregnant women.FiguresReferencesRelatedDetailsCited by Marko T, Suarez M, Todorova E, Mark C and Julie P (2020) A Scoping Review of Nurses' Contributions to Health-Related, Wildfire Research, Annual Review of Nursing Research, 10.1891/0739-6686.38.73, 38:1, (73-96), Online publication date: 23-Dec-2019. Related articlesBirth Weight following Pregnancy during the 2003 Southern California Wildfires29 May 2012Environmental Health Perspectives Vol. 120, No. 9 September 2012Metrics About Article Metrics Publication History Originally published31 August 2012Published in print1 September 2012 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.