Prenatal exposure to ambient air pollution is associated with neurodevelopmental outcomes at 2 years of age

Abstract

Background: Higher prenatal ambient air pollution exposure has been associated with impaired neurodevelopment in preschoolers and school-aged children. The purpose of this study was to explore the relationships between prenatal ambient air pollution exposure and neurodevelopment during infancy.

Methods: This study examined 161 Latino mother-infant pairs from the Southern California Mother's Milk Study. Exposure assessments included prenatal nitrogen dioxide (NO₂) and particulate matter smaller than 2.5 and 10 microns in diameter (PM_2.5 and PM₁₀, respectively). The pregnancy period was also examined as three windows, early, mid, and late, which describe the first, middle, and last three months of pregnancy. Infant neurodevelopmental outcomes at 2 years of age were measured using the Bayley-III Scales of Infant and Toddler Development. Multivariable linear models and distributed lag linear models (DLM) were used to examine relationships between prenatal exposures and neurodevelopmental scores, adjusting for socioeconomic status, breastfeeding frequency, time of delivery, pre-pregnancy body mass index, and infant birthweight and sex.

Results: Higher prenatal exposure to PM₁₀ and PM_2.5 was negatively associated with composite cognitive score (β = -2.01 [-3.89, -0.13] and β = -1.97 [-3.83, -0.10], respectively). In addition, higher average prenatal exposure to PM₁₀ was negatively associated with composite motor (β = -2.35 [-3.95, -0.74]), scaled motor (β = -0.77 [-1.30, -0.24]), gross motor (β = -0.37 [-0.70, -0.04]), fine motor (β = -0.40 [-0.71, -0.09]), composite language (β = -1.87 [-3.52, -0.22]), scaled language (β = -0.61 [-1.18, -0.05]) and expressive communication scaled scores (β = -0.36 [-0.66, -0.05]). DLMs showed that higher prenatal air pollution exposure during mid and late pregnancy was inversely associated with motor, cognitive, and communication language scores.

Conclusions: Higher exposure to air pollutants during pregnancy, particularly in the mid and late prenatal periods, was inversely associated with scaled and composite motor, cognitive, and language scores at 2 years. These results indicate that prenatal ambient air pollution may negatively impact neurodevelopment in early life.

Keywords: Air Pollution; Child Development; Health Disparities; Neurodevelopment; Pregnancy Exposures.

Fig. 1

Correlations Among Exposure Windows During the 9-Month Pregnancy Period. Figures show the Spearman correlation structure among individual monthly lags of prenatal ambient air pollution exposure for NO₂ (left), PM₁₀ (middle), and PM_2.5 (right). Blue colors indicate positive correlations while red colors indicate negative correlations. Statistical significance is denoted as *p < 0.05, **p < 0.01, and ***p < 0.001, respectively

Fig. 2

Associations Between Prenatal PM₁₀ Exposure and Composite Cognitive, Motor, and Language Scores at 2 Years. Average prenatal exposure to PM₁₀ (µg/m³) was inversely associated with composite cognitive score (A), composite motor score (B), and composite language score (C). Unadjusted plots and regression lines for neurodevelopmental scores and prenatal PM₁₀ are shown. Figures show betas (β) and 95% confidence intervals (CIs) that were scaled to a 1SD difference in exposure (SD NO₂ = 2.43 ppb, SD PM₁₀ = 3.94 µg/m³, SD PM_2.5 = 1.24 µg/m³) from multivariable linear regression models that adjusted for socioeconomic status (SES), breast feedings per day, gestational age, pre-pregnancy BMI, infant birthweight, and infant sex

Fig. 3

Associations Between PM₁₀ and PM_2.5 Exposure During Mid to Late Pregnancy and Composite Cognitive Scores at 2 Years. Figures show effect sizes and 95% confidence intervals (CI) at each monthly lag of exposure during the pregnancy period. Results were obtained from distributed lag models (DLMs) that adjusted for socioeconomic status (SES), breast feedings per day, gestational age, pre-pregnancy BMI, infant birthweight, and infant sex. Panels show associations between PM_2.5 and composite cognitive score (A), PM₁₀ and composite cognitive score (B). Effect sizes are scaled by the IQR of each respective pollutant (PM₁₀ = 8 µg/m³, PM_2.5 = 3 µg/m³). Statistically significant windows are denoted by red squares (p < 0.05)

Fig. 4

Associations Between PM₁₀ Exposure During Mid and Late Pregnancy and Motor Scores at 2 Years. Figures show effect sizes and 95% confidence intervals (CI) at each monthly lag of exposure during the pregnancy period. Results were obtained from distributed lag models (DLMs) that adjusted for socio-economic status, breast feedings per day, gestational age, pre-pregnancy BMI, infant birthweight, and infant sex. Panels show associations between PM₁₀ and composite motor score (A), scaled motor score (B), gross motor score (C) and fine motor score (D). Effect sizes are scaled by the IQR (PM₁₀ = 8 µg/m³). Statistically significant windows are shown in red (p < 0.05)

Fig. 5

Associations between PM_2.5 Exposure During Mid to Late Pregnancy and Motor Scores at 2 Years. Figures show effect sizes and 95% confidence intervals (CI) at each monthly lag of exposure during the pregnancy period. Results were obtained from distributed lag models (DLMs) that adjusted for socio-economic status, breast feedings per day, gestational age, pre-pregnancy BMI, infant birthweight, and infant sex. Panels show associations between PM_2.5 and composite motor score (A), scaled motor score (B), and fine motor score (C). Effect sizes are scaled by the IQR (PM_2.5 = 3 µg/m³). Statistically significant windows are shown in red (p < 0.05)