Global Push: Multicontinent Project Assesses Particulate Matter and Birth Weight
Tanya Tillett, MA, of Durham, NC, is a staff writer/editor for EHP. She has been on the EHP staff since 2000 and has represented the journal at national and international conferences.
Maternal exposure to ambient air pollution has been associated with a number of adverse pregnancy outcomes including low birth weight, defined as a full-term infant weighing less than 2,500 g (about 5 lb, 8 oz) at birth. But it’s been difficult to translate these findings into health-protective policies because of inconsistencies across studies—something the International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO) is working to remedy. This worldwide, multicenter project used a common analysis protocol to derive combined effect estimates of maternal exposure to coarse and fine particulate matter (PM10 and PM2.5, respectively) and to assess differences in how the centers conducted their individual studies [EHP 121(3):367–373; Dadvand et al.].
ICAPPO researchers at 14 centers in 9 countries generated effect estimates for ambient PM10 and PM2.5 in relation to more than 3 million live, singleton, term births. For this analysis, the authors used a meta-analysis approach to synthesize contributing factors such as study setting, availability of air pollutant data, birth data, and maternal socioeconomic status. They estimated combined effects across centers and used meta-regression analysis to determine how each center’s particular characteristics and exposure assessment methods influenced differences in effect estimates among centers. All these factors can contribute to variation in results across studies.
Higher maternal exposure to PM10 and PM2.5 was associated with lower birth weight across the study population. The investigators found a positive association between low birth weight and increased PM10 and PM2.5 exposure during the entire pregnancy, as well as a negative association between increased PM10 exposure and term birth weight when all averages were compared.
Differences in average PM2.5 exposure levels and PM2.5/PM10 ratios influenced effect estimate outcomes—centers with higher PM2.5 levels and higher PM2.5/PM10 ratios reported stronger associations with birth weight. These findings could indicate a geographical variation in the association between air pollution and low birth weight. Meta-regression analyses also showed that centers reported stronger associations if they conducted a temporal exposure assessment only (i.e., exposure was determined according to the time period that each woman was pregnant) compared with those that accounted for both spatial and temporal elements of exposure (i.e., exposure was determined by time of pregnancy and where the woman lived).
Although the study does not include direct measurements of personal exposure levels, it does provide a comprehensive estimate of the global effects of maternal exposure to particulate matter on birth weight. This could prove useful for shaping meaningful public health policies regarding air pollution.
EHP is pleased to announce that it is now operating under a continuous publication workflow! As indicated in a previous announcement, continuous publication allows EHP to post new content online throughout the month, as each paper becomes ready for an issue. This gets content out to our readers much more quickly than the old issue-based model, and unlike our previous Advance Publication model, these are final, edited articles. (more…)
EHP is pleased to announce that Prenatal Exposure to Glycol Ethers and Neurocognitive Abilities in 6-Year-Old Children: The PELAGIE Cohort Study, published in EHP on 14 October 2016, has been selected by the Children’s Environmental Health Network (CEHN) as its May 2017 Article of the Month. CEHN Article of the Month summaries discuss the potential policy implications of current children’s environmental health research. The CEHN summary can be viewed here.
Among the Resources now available on our Children’s Health page is the text of Executive Order 13045, “Protection of Children from Environmental Health Risks and Safety Risks” (21 April 1997). The Executive Order noted the particular vulnerabilities of children to environmental hazards, codified the need to identify and alleviate such risks, and created the President’s Task Force on Environmental Health Risks and Safety Risks to Children to identify data resources and promote research in these areas. As we mark 20 years since the order was enacted, we can see how these efforts have produced important research and mitigation of hazards—a strong base for continued work on behalf of children’s environmental health.