Traffic-related metrics and adverse birth outcomes: A systematic review and meta-analysis

Exposure to Traffic Density during Pregnancy and Birth Weight in a National Cohort, 2000–2017

“…In addition, they evaluated studies that treated traffic as a binary variable depending on the distance to the road. A positive effect between LBW and the distance to road was found as well, showing an OR of 1.044 (95% CI: 1.020, 1.068) when the cut-off point was 50 m and an OR of 1.023 (95% CI: 1.002, 1.042) with a distance of 100 m [ 15 ].…”

“…As regard to the different proxies to the exposure, several studies investigated the effect of traffic-related air pollution using prediction models to estimate air pollution by calculating daily concentrations of PM, specifically PM 2.5 and PM 10 , and other pollutants, such as SO 2 , CO, NO 2 and O 3 , nearby the study groups [ 9 , 34 , 35 , 36 ]. Conversely, for the present study, we decided to use traffic density, calculated within circular buffers in meters on maternal home address based on AADT, due to the difficulty of having prediction models for the whole country during the 18 years of study, as well that traffic density can be considerate as a more valuable indicator of traffic-related pollution than streets length or the distance to roads [ 15 ].…”

“…Also, their harmful effect on birth outcomes have been displayed in several studies [ 2 , 10 , 11 , 12 ], and it has been estimated that about 100,000 of deaths per year worldwide could be linked to this exposure [ 9 ]. Recent meta-analyses have highlighted the significant association between air pollution due to traffic and LBW [ 13 , 14 , 15 ] and more studies have shown how adverse birth effects were linked to maternal residential proximity to a mayor traffic density area, to heavy traffic lights, to bus stations, and to several ring and major roads [ 9 , 16 , 17 , 18 , 19 , 20 ]. To support this evidence, it has been shown that air pollution can lead to an increase in cell proliferation, organ development changes and modification on fetal metabolism, that can cause especial vulnerability and damage during the states of pregnancy and the neonatal period [ 21 , 22 , 23 , 24 , 25 ].…”

“…Measuring traffic air pollution could be approached by different strategies, such as direct air quality monitoring, modeling air pollution, or distance to road or traffic density [ 13 , 14 , 15 ]. The correlation between air quality and traffic flow [ 6 ] makes possible to accurately estimate air pollution exposure using traffic density [ 15 ].…”

“…Measuring traffic air pollution could be approached by different strategies, such as direct air quality monitoring, modeling air pollution, or distance to road or traffic density [ 13 , 14 , 15 ]. The correlation between air quality and traffic flow [ 6 ] makes possible to accurately estimate air pollution exposure using traffic density [ 15 ]. The definition of traffic density is the number of vehicles that fill a lane of a roadway section at a point of time, expressed as vehicles per mile or kilometers [ 26 ] and it has been shown that as traffic volume increases in a road, pollutant emission increases as well [ 27 , 28 ].…”