Identifying environmental risk factors for human neural tube defects before and after folic acid supplementation

Table 3 Multivariate regression analyses of the association between environmental factors and NTDs as the dependent variable

Model (R²) and Independent Variables	Standardized Coefficients	t	P	Std. Error
Rates for the 1998-2001 period in the buffer region of 7-12 km (0.415)
doctor	0.511	3.683	0.001	7.096
Rates for the 2002-2005 period in the buffer region of 7-12 km (0.242)
fruit	-0.479	-2.298	0.028	15.020
pollution	0.380	2.337	0.026	0.003
Distance to faults	-0.531	-2.617	0.013	0.003
Rates for the 1998-2001 period in the buffer region of 13-18 km (0.191)
elevation	0.437	2.380	0.026	0.146
Rates for the 2002-2005 period in the buffer region of 13-18 km (0.711)
doctor	-0.717	-5.848	0.000	8.693
distance to roads	0.440	3.640	0.002	0.004
distance to rivers	-0.323	-2.618	0.016	0.002
Rates for the 1998-2001 period in the buffer region of 25-30 km (0.486)
fertilizer	0.540	3.177	0.005	0.640
elevation	0.392	2.308	0.033	0.153
Rates for the 2002-2005 period in the buffer region of 25-30 km (0.362)
gradient	0.602	3.283	0.004	1.836