Abstract
BackgroundDevelopmental exposure to particulate matter (PM) air pollution may impair children’s behaviors. Our objectives were to quantify the impact of reducing indoor PM using portable HEPA filter air cleaners during pregnancy on behavioral problems in children and to assess associations between indoor fine PM (PM2.5) concentrations during pregnancy and children’s behavior.MethodsThis is a secondary analysis of a single-blind parallel-group randomized controlled trial in which we randomly assigned 540 non-smoking pregnant women to receive 1 or 2 HEPA filter air cleaners or no air cleaners. We administered the Behavior Assessment System for Children (BASC-3) to caregivers when children were a mean age of 23 months, and again at a mean age of 48 months. Primary outcomes were the four BASC-3 composite scales: externalizing problems, internalizing problems, adaptive skills, and the behavioral symptoms index. We imputed missing data using multiple imputation with chained equations. The primary analysis was by intention-to-treat. In a secondary analysis, we evaluated associations between BASC-3 composite indices and modeled trimester-specific PM2.5 concentrations inside residences.ResultsWe enrolled participants at a median of 11 weeks gestation. After excluding miscarriages, still births and neonatal deaths, our analysis included 478 children (233 control and 245 intervention). We observed no differences in the mean BASC-3 scores between treatment groups. An interquartile increase (20.1 µg/m3) in first trimester PM2.5 concentration was associated with higher externalizing problem scores (2.4 units, 95% CI: 0.7, 4.1), higher internalizing problem scores (2.4 units, 95% CI: 0.7, 4.0), lower adaptive skills scores (-1.5 units, 95% CI: -3.0, 0.0), and higher behavior symptoms index scores (2.3 units, 95% CI: 0.7, 3.9). Third trimester PM2.5 concentrations were also associated with some behavioral indices at age 4, but effect estimates were smaller. No significant associations were observed with PM2.5 concentrations during the second trimester or for any of the BASC indices when children were 2 years old.ConclusionWe found no benefit of reducing indoor particulate air pollution during pregnancy on parent-reported behaviors in children. Associations between indoor PM2.5 concentrations in the first trimester and behavioral scores among 4-year old children suggest that it may be necessary to intervene early in pregnancy to protect children, but these exploratory findings should be interpreted cautiously.Trial registrationClinicalTrials.gov: NCT01741051
Highlights
Exposure to fine particulate matter air pollution (PM2.5) during pregnancy is linked to impaired fetal growth [1, 2], which may in turn cause developmental programming that adversely affects health in childhood and beyond [3]
We evaluated the associations between Behavior Assessment System for Children (BASC-3) composite indices and trimester-specific and full-pregnancy averaged indoor PM2.5 concentrations estimated from a previously developed model of weekly concentrations [30]
Variance inflation factors were < 1.7 for all variables. In this cohort of women living in a heavily polluted community, we found no evidence that reducing indoor particulate matter with high efficiency particulate air (HEPA) air cleaners starting late in the Maternal blood lead concentration in late pregnancy ug/dL Missing, n (%) Type of birth Cesarean Vaginal Missing, n (%) Preterm birth Preterm (< 37 weeks) Full tern (≥ 37 weeks) Missing, n (%) Birth weight, grams Missing, n (%) Child’s sex Female Male Missing, n (%) Child’s blood lead concentration at age 2, ug/dL Missing, n (%) Maternal depression level (BDI) at 2-year visit Mild Moderate to severe Missing, n (%) Maternal Wechsler Abbreviated Scale of Intelligence (WASI) matrix reasoning raw score Missing, n (%) Maternal WASI vocabulary raw score Missing, n (%)
Summary
Exposure to fine particulate matter air pollution (PM2.5) during pregnancy is linked to impaired fetal growth [1, 2], which may in turn cause developmental programming that adversely affects health in childhood and beyond [3]. Evidence from animal and epidemiologic studies suggests that prenatal exposure to air pollution may adversely affect brain development [4,5,6]. Investigators have not definitively identified the biological mechanism(s) through which air pollution exposure in pregnancy may impact brain development, but such a link is biologically plausible. Animal experiments have suggested that prenatal exposure to airborne particles induces inflammation in mothers followed by changes in brain morphology in the offspring [4, 18]. Developmental exposure to particulate matter (PM) air pollution may impair children’s behaviors. Our objectives were to quantify the impact of reducing indoor PM using portable HEPA filter air cleaners during pregnancy on behavioral problems in children and to assess associations between indoor fine PM (PM2.5) concentrations during pregnancy and children’s behavior
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