Table 4

Relative risks of category of anomalies according to exposure index, road traffic, income, and population density (exposed communities only)

Variables	Minor (n = 518)		Chromosomal (n = 204)		Monogenic (n = 83)		Other major anomalies (n = 964)
Variables	RR2†	95% CI	RR2†	95% CI	RR2†	95% CI	RR2†	95% CI
Expected number adjusted for 10 years (1988–97), seven classes of maternal (<20, 20–24, 25–29, 30–34, 35–39, 40–44, ⩾45), and eight departments.
†RR2 estimates with all four variables in the model.
p: degree of significance of the linear trend test.
Exposure index
Low	1.00		1.00		1.00		1.00
Medium	0.86	0.65 to 1.14	0.99	0.66 to 1.48	0.70	0.38 to 1.31	0.91	0.73 to 1.13
High	1.09	0.82 to 1.45	1.09	0.75 to 1.60	0.89	0.48 to 1.66	0.98	0.79 to 1.21
	NS		NS		NS		NS
Road traffic (vehicles/day)
<10 000	1.00		1.00		1.00		1.00
10–50000	1.14	0.82 to 1.59	1.47	0.97 to 2.23	0.77	0.35 to 1.72	1.24	0.97 to 1.58
>50000	1.04	0.77 to 1.39	0.90	0.60 to 1.37	1.39	0.72 to 2.70	1.39	1.11 to 1.74
	NS		NS		NS		p = 0.01
Family income (€/y)
<11400	1.00		1.00		1.00		1.00
11400–13700	1.16	0.87 to 1.54	1.19	0.77 to 1.83	0.79	0.42 to 1.47	1.15	0.91 to 1.45
13700–16000	1.41	] 1.00 to 2.00	1.50	0.91 to 2.47	0.54	0.23 to 1.26	1.62	1.25 to 2.11
>16000	0.85	0.58 to 1.24	1.23	0.74 to 2.04	0.60	0.27 to 1.33	1.00	0.75 to 1.34
	NS		NS		NS		NS
Population density (inh/km²)
<100	1.00		1.00		1.00		1.00
100–500	1.53	0.85 to 2.74	1.55	0.63 to 3.81	0.88	0.29 to 2.66	1.39	0.93 to 2.07
500–1000	1.61	0.91 to 2.87	1.86	0.77 to 4.51	0.85	0.28 to 2.52	1.04	0.69 to 1.57
>1000	1.69	0.94 to 3.03	2.38	0.98 to 5.78	0.83	0.27 to 2.52	1.07	0.71 to 1.61
	NS		p = 0.02		NS		NS