Residential traffic exposure and pregnancy-related outcomes: a prospective birth cohort study

Table 2 Covariate-adjusted associations between residential traffic exposure and birth outcomes.

	Birth weight (g) ^b	Small for gestational age^c (n of cases)	Preterm birth^c (n of cases)
Distance-weighted traffic density (veh/24 h*m) ^a
< 158,503	Reference	Reference (n = 61)	Reference (n = 84)
158,503 - 546,770	-20 (-47, 8)	0.94 (0.65, 1.36) (n = 60)	1.37 (1.02, 1.84) * (n = 112)
546,770 - 1,235,384	-9 (-37, 18)	0.99 (0.69, 1.43) (n = 62)	1.33 (0.98, 1.79) † (n = 110)
> 1,235,384	6 (-21, 34)	1.12 (0.78, 1.59) (n = 74)	1.18 (0.87, 1.59) (n = 100)
Distance to major road (m)
> 200 (n = 2646)	Reference	Reference (n = 82)	Reference (n = 134)
150-200 (n = 1066)	-21 (-52, 9)	1.00 (0.67, 1.49) (n = 38)	1.09 (0.79, 1.50) (n = 59)
100-150 (n = 1258)	-41 (-69, -12) *	1.01 (0.69, 1.48) (n = 44)	1.13 (0.84, 1.52) (n = 75)
50-100 (n = 1302)	8 (-20, 37)	1.12 (0.78, 1.62) (n = 51)	1.08 (0.80, 1.45) (n = 74)
0-50 (n = 1067)	-6 (-36, 24)	1.14 (0.77, 1.68) (n = 42)	1.15 (0.84, 1.58) (n = 64)

* p < 0.05
† p < 0.10
^a Values listed are the <25^th, 25-50^th, 50-75^th and >75^th percentiles of the DWTD values.
^b Values are regression coefficients (95% confidence interval) and reflect the difference in birth weight for change in traffic parameters. Analyses are based on 7,288 subjects. The model is adjusted for gestational age, fetal sex, maternal age, maternal education, maternal ethnicity, maternal body mass index, parity, maternal smoking, maternal alcohol consumption, month of birth, and year of birth.
^c Values are odds ratios (95% confidence interval) and reflect the risk for adverse birth outcomes for change in traffic parameters. Analyses are based on 7,278 subjects for small for gestational age at birth and 7,337 subjects for preterm birth. Models are adjusted for fetal sex, maternal age, maternal education, maternal ethnicity, maternal body mass index, parity, maternal smoking, maternal alcohol consumption, month of birth, and year of birth.

ISSN: 1476-069X