Longitudinal associations of in utero and early life near-roadway air pollution with trajectories of childhood body mass index

Abstract

BackgroundEvidence suggests that childhood near-roadway air pollution (NRAP) exposures contribute to increased body mass index (BMI); however, effects of NRAP exposure during the vulnerable periods including in utero and first year of life have yet to be established. In this study, we examined whether exposure to elevated concentrations of NRAP during in utero and/or first year of life increase childhood BMI growth.MethodsParticipants in the Children’s Health Study enrolled from 2002 to 2003 with annual visits over a four-year period and who changed residences before study entry were included (n = 2318). Annual height and weight were measured and lifetime residential NRAP exposures including in utero and first year of life periods were estimated by nitrogen oxides (NOx) using the California line-source dispersion model. Linear mixed effects models assessed in utero or first year near-road freeway and non-freeway NOx exposures and BMI growth after adjusting for age, sex, race/ethnicity, parental education, Spanish questionnaire, and later childhood near-road NOx exposure.ResultsA two-standard deviation difference in first year of life near-road freeway NOx exposure was associated with a 0.1 kg/m2 (95% confidence interval (CI): 0.03, 0.2) faster increase in BMI growth per year and a 0.5 kg/m2 (95% CI: 0.02, 0.9) higher attained BMI at age 10 years.ConclusionsHigher exposure to early life NRAP increased the rate of change of childhood BMI and resulted in a higher attained BMI at age 10 years that were independent of later childhood exposures. These findings suggest that elevated early life NRAP exposures contribute to increased obesity risk in children.Electronic supplementary materialThe online version of this article (10.1186/s12940-018-0409-7) contains supplementary material, which is available to authorized users.

Maternal and early‐life area‐level characteristics and childhood adiposity: A systematic review

“…Fleisch et al found no association between PM 2.5 exposure in the third trimester and BMI z‐scores, skinfold fat, waist circumference, or fat mass in either early (median age 3.3) or mid‐ (median age 7.7) childhood, after adjusting for maternal education. Kim et al found that PM 2.5 exposure was negatively associated with BMI at age 10, for exposure across pregnancy (per 17 parts per billion PM 2.5 change in BMI −0.60 kg/m 2 , 95% CI, −1.10‐0.10) and across the first year of life (per 14.8 parts per billion PM 2.5 change in BMI −0.50 kg/m 2 , 95% CI, −0.90 to −0.02), adjusting for maternal education. Mao et al found positive associations between greater quartiles of exposure to PM 2.5 at preconception (90 days before pregnancy), all three trimesters and an average across trimesters, in regard to the risk of children being affected by overweight or obesity between the ages of 2 and 9 years, adjusting for maternal education and household income.…”

“…Two duplicate studies conducted by the same lead authors using the same dataset were identified, one study was retained as environmental measures were included in the fully adjusted model, whereas they were not in the other study. In total, eight studies were included in the narrative synthesis . Four studies were based in the United States, one each in Canada, Denmark, England, and South Korea.…”

“…All eight included studies used data from prospective cohorts. Four studies recruited women during pregnancy, one study recruited shortly after birth, one study used a combination of the two, one study recruited 9 months after birth, and one study recruited children through schools . The recruitment rate varied between 12% and 78% (mean 51%) and was not presented in two studies .…”

“…All outcomes were measured by research assistants, school nurses, or GPs, with the exception of one study, where the measurer of height and weight was “undefined” for 35% of the sample . BMI was the most common outcome and was present in five studies (four used age‐ and sex‐adjusted z‐scores, one did not). An age‐ and sex‐ adjusted cut‐off for overweight/obesity was used in four studies, and fat mass was assessed in two studies .…”

“…Adjusting for maternal education, black carbon exposure during the third trimester was not associated with BMI z‐scores, skinfold fat, waist circumference, or fat mass in either early‐ (median age 3.3) or mid‐ (median age 7.7) childhood . Kim et al examined sources of NO x exposure, and the association with adiposity, adjusting for maternal education and income. NO x exposure from freeway sources averaged across the entire pregnancy was not associated with BMI at age 10, but there was an association for exposure in pregnancy among a subgroup who did not move home by 6 years of age (increase in BMI per 40.3 parts per billion NO x 0.70 kg/m 2 , 95% CI, 0.07‐1.30).…”