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

Table 3 Covariate-adjusted associations between residential traffic exposure and pregnancy complications.

	Pregnancy-induced hypertension^b (n of cases)	(Pre)eclampsia or HELLP^b (n of cases)	Gestational diabetes^b (n of cases)
Distance-weighted traffic density (veh/24 h*m) ^a
< 158,503	Reference (n = 64)	Reference (n = 34)	Reference (n = 15)
158,503 - 546,770	1.00 (0.69, 1.45) (n = 59)	0.94 (0.57, 1.55) (n = 31)	0.69 (0.30, 1.57) (n = 10)
546,770 - 1,235,384	0.90 (0.62, 1.30) (n = 59)	1.12 (0.70, 1.79) (n = 39)	1.07 (0.51, 2.23) (n = 15)
> 1,235,384	1.07 (0.75, 1.53) (n = 68)	1.14 (0.71, 1.82) (n = 40)	0.79 (0.35, 1.81) (n = 10)
Distance to major road (m)
> 200 (n = 2646)	Reference (n = 93)	Reference (n = 54)	Reference (n = 19)
150-200 (n = 1066)	0.88 (0.57, 1.36) (n = 29)	0.74 (0.42, 1.29) (n = 17)	1.07 (0.47, 2.44) (n = 9)
100-150 (n = 1258)	0.94 (0.64, 1.39) (n = 39)	0.96 (0.59, 1.56) (n = 25)	0.77 (0.32, 1.88) (n = 7)
50-100 (n = 1302)	1.07 (0.75, 1.54) (n = 49)	0.85 (0.52, 1.38) (n = 24)	1.13 (0.51, 2.50) (n = 10)
0-50 (n = 1067)	1.08 (0.74, 1.60) (n = 40)	1.03 (0.63, 1.69) (n = 24)	0.68 (0.25, 1.86) (n = 5)

^a Values listed are the <25^th, 25-50^th, 50-75^th and >75^th percentiles of the DWTD values.
^b Values are odds ratios (95% confidence interval) and reflect the risk for pregnancy complications for change in traffic parameters. Analyses are based on 7,108 subjects for pregnancy-induced hypertension and for (pre)eclampsia or HELLP, and on 7,068 subjects for gestational diabetes. Models are adjusted for maternal age, maternal education, maternal ethnicity, maternal body mass index, parity, maternal smoking, maternal alcohol consumption, month of birth, and year of birth.

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