Table 4

Associations between PM2.5 and NO2 exposure in different pregnancy periods and mental and psychomotor developmental delay

Crude modelsAdjusted models*Co-exposure models†
Per IQR increase inMDD (95% CI)PDD (95% CI)MDD (95% CI)PDD (95% CI)MDD (95% CI)PDD (95% CI)
(N=946)(N=946)(N=945)(N=945)(N=945)(N=945)
Estimated exposure to PM2.590 days prior to conception1.45 (1.16 to 1.83)1.49 (1.20 to 1.83)0.95 (0.64 to 1.42)2.12 (1.45 to 3.11)0.97 (0.63 to 1.51)1.78 (1.17 to 2.71)
First trimester1.05 (0.83 to 1.33)1.04 (0.84 to 1.28)1.14 (0.73 to 1.79)1.42 (0.96 to 2.11)1.35 (0.80 to 2.25)1.16 (0.74 to 1.82)
Second trimester0.63 (0.49 to 0.80)0.77 (0.63 to 0.95)0.81 (0.54 to 1.22)0.72 (0.51 to 1.02)0.83 (0.52 to 1.31)0.57 (0.38 to 0.85)
Third trimester1.23 (0.96 to 1.58)1.19 (0.95 to 1.49)1.25 (0.82 to 1.90)1.17 (0.80 to 1.70)1.39 (0.87 to 2.23)0.98 (0.64 to 1.49)
Total pregnancy0.84 (0.69 to 1.03)0.98 (0.82 to 1.18)1.07 (0.82 to 1.39)1.07 (0.84 to 1.35)1.17 (0.86 to 1.59)0.90 (0.68 to 1.20)
Estimated exposure to NO290 days prior to conception1.20 (0.99 to 1.45)1.41 (1.19 to 1.67)0.97 (0.77 to 1.21)1.42 (1.16 to 1.75)0.97 (0.76 to 1.25)1.24 (0.99 to 1.56)
First trimester0.97 (0.80 to 1.17)1.18 (0.99 to 1.40)0.91 (0.72 to 1.13)1.29 (1.05 to 1.58)0.84 (0.65 to 1.09)1.24 (0.99 to 1.57)
Second trimester0.79 (0.66 to 0.95)1.04 (0.88 to 1.22)0.94 (0.76 to 1.15)1.14 (0.95 to 1.38)0.98 (0.77 to 1.24)1.31 (1.06 to 1.63)
Third trimester1.04 (0.85 to 1.28)1.25 (1.04 to 1.50)0.94 (0.73 to 1.21)1.27 (1.01 to 1.60)0.86 (0.65 to 1.14)1.28 (0.99 to 1.65)
Total pregnancy0.92 (0.79 to 1.07)1.16 (1.01 to 1.33)0.94 (0.80 to 1.11)1.17 (1.02 to 1.36)0.9 (0.75 to 1.08)1.21 (1.02 to 1.43)
  • All significant findings in the table are bold.

  • *Models adjusted for maternal age at enrolment, infant’s sex, maternal BMI at 11–14 weeks’ gestation, primiparity, monthly household income level and season of births.

  • †Models adjusted for maternal age at enrolment, infant’s sex, maternal BMI at 11–14 weeks’ gestation, primiparity, monthly household income level and season of births, and adjusted for the other air pollutant.

  • BMI, body mass index; MDD, mental developmental delay; NO2, nitrogen dioxide ; PDD, psychomotor developmental delay; PM2.5, particulate matter with diameter ≤2.5.