Table 3

Relative risks for term low birth weight according to trimester-specific exposure to air pollutants.



Unadjusted* RR (95% CI)
Adjusted** RR (95%CI)
Adjusted for Birth Year*** RR (95%CI)


1stTrimester
O3

< 25th percentile (referent)

25 – 50th percentile
1.15 (0.89, 1.50)
1.16 (0.88, 1.53)
1.11 (0.83, 1.47)

51 – 75th percentile
1.11 (0.85, 1.45)
1.04 (0.79, 1.37)
1.02 (0.77, 1.36)

> 75th percentile
1.06 (1.80, 1.40)
1.01 (0.75, 1.35)
1.00 (0.74, 1.34)

Continuous****
1.01 (0.90, 1.14)
0.98 (0.86, 1.11)
0.98 (0.86, 1.12)
SO2

< 25th percentile (referent)

25 – 50th percentile
0.93 (0.71, 1.22)
0.96 (0.73, 1.28)
0.98 (0.74, 1.31)

51 – 75th percentile
1.15 (0.87, 1.52)
1.18 (0.88, 1.58)
1.12 (0.84, 1.50)

> 75th percentile
1.30 (1.00, 1.67)
1.36 (1.04, 1.78)
1.26 (0.96, 1.66)

Continuous****
1.17 (1.02, 1.33)
1.20 (1.05, 1.38)
1.15 (1.00, 1.31)
PM10

< 25th percentile (referent)

25 – 50th percentile
1.24 (0.95, 1.62)
1.24 (0.94, 1.64)
1.14 (0.86, 1.52)

51 – 75th percentile
1.25 (0.96, 1.62)
1.24 (0.95, 1.64)
1.08 (0.82, 1.44)

> 75th percentile
1.28 (1.00, 1.65)
1.33 (1.02, 1.74)
1.11 (0.84, 1.48)

Continuous****
1.09 (1.00, 1.18)
1.09 (1.00, 1.19)
1.03 (0.94, 1.14)

2ndTrimester
O3

< 25th percentile (referent)

25 – 50th percentile
0.99 (0.76, 1.30)
0.93 (0.70, 1.23)
0.90 (0.67, 1.20)

51 – 75th percentile
1.13 (0.87, 1.45)
1.07 (0.82, 1.40)
1.07 (0.81, 1.41)

> 75th percentile
1.01 (0.76, 1.33)
0.98 (0.73, 1.31)
0.98 (0.73, 1.30)

Continuous****
1.03 (0.92, 1.17)
1.03 (0.91, 1.18)
1.04 (0.91, 1.18)
SO2

< 25th percentile (referent)

25 – 50th percentile
1.14 (0.89, 1.47)
1.12 (0.86, 1.46)
1.14 (0.88, 1.49)

51 – 75th percentile
1.05 (0.80, 1.37)
1.13 (0.85, 1.50)
1.09 (0.82, 1.45)

> 75th percentile
0.92 (0.71, 1.20)
1.04 (0.79, 1.37)
0.99 (0.75, 1.32)

Continuous****
0.93 (0.82, 1.05)
0.99 (0.87, 1.13)
0.97 (0.85, 1.11)
PM10

< 25th percentile (referent)

25 – 50th percentile
0.98 (0.76, 1.28)
1.02 (0.77, 1.34)
0.99 (0.75, 1.31)

51 – 75th percentile
1.09 (0.84, 1.40)
1.16 (0.89, 1.51)
1.10 (0.84, 1.45)

> 75th percentile
1.00 (0.77, 1.28)
1.09 (0.83, 1.42)
1.01 (0.76, 1.34)

Continuous****
1.00 (0.91, 1.09)
1.02 (0.93, 1.12)
1.00 (0.90, 1.10)

3rdTrimester
O3

< 25th percentile (referent)

25 – 50th percentile
0.85 (0.64, 1.13)
0.89 (0.66, 1.19)
0.86 (0.64, 1.16)

51 – 75th percentile
0.94 (0.72, 1.22)
0.95 (0.72, 1.25)
0.94 (0.71, 1.25)

> 75th percentile
0.89 (0.67, 1.18)
1.01 (0.75, 1.36)
1.03 (0.76, 1.38)

Continuous****
0.94 (0.83, 1.07)
1.00 (0.87, 1.15)
1.01 (0.88, 1.16)
SO2

< 25th percentile (referent)

25 – 50th percentile
1.05 (0.82, 1.34)
1.04 (0.80, 1.34)
1.03 (0.80, 1.34)

51 – 75th percentile
0.80 (0.60, 1.07)
0.85 (0.63, 1.15)
0.81 (0.60, 1.10)

> 75th percentile
0.87 (0.68, 1.13)
0.88 (0.67, 1.15)
0.82 (0.63, 1.08)

Continuous****
0.91 (0.80, 1.03)
0.93 (0.81, 1.06)
0.89 (0.78, 1.02)
PM10

< 25th percentile (referent)

25 – 50th percentile
0.93 (0.72, 1.20)
0.96 (0.73, 1.26)
0.92 (0.70, 1.21)

51 – 75th percentile
1.07 (0.83, 1.37)
1.14 (0.88, 1.48)
1.04 (0.80, 1.36)

> 75th percentile
0.92 (0.71, 1.18)
1.03 (0.79, 1.35)
0.92 (0.69, 1.22)

Continuous****
0.95 (0.87, 1.05)
0.99 (0.89, 1.09)
0.94 (0.85, 1.05)

* Unadjusted model has only air pollution and no other covariates

** Adjusted for gender of infant, gestational age, maternal age, parity, smoking during pregnancy, weight change, prior neonatal deaths, prior stillbirth, prior low birth weight and neighborhood family income.

*** Adjusted for birth year, gender of infant, gestational age, maternal age, parity, smoking during pregnancy, weight change, prior neonatal deaths, prior stillbirth, prior low birth weight and neighborhood family income.

**** RR for continuous model based on inter quartile range

Dugandzic et al. Environmental Health: A Global Access Science Source 2006 5:3   doi:10.1186/1476-069X-5-3