Table 3.

The incidences of birth defects in rural and urban areas and the proportions of relative factors in Xi’an city from 2003 To 2012

Year	Perinatals (n)		Urban		Rural		Birth defects with LBW		Birth defects with normal birth weight		χ2	P	Contingency coefficient	Prenatal diagnosis (n)	Postpartum diagnosis (n)
	Urban	Rural	n	Incidence (%)	n	Incidence (%)	n	Incidence (%)	n	Incidence (%)
2003	22,601	19,671	183	8.10	205	10.42	124	12.30	264	0.64	1471.42	<0.001	0.1834	127	261
2004	25,659	22,830	200	7.79	217	9.51	117	10.53	299	0.63	1247.35	<0.001	0.1584	115	302
2005	27,497	27,330	170	6.18	247	9.04	97	6.78	310	5.99	705.61	<0.001	0.1127	121	296
2006	28,873	29,780	207	7.17	254	8.53	132	7.67	329	0.58	1076.73	<0.001	0.1343	136	325
2007	39,994	40,536	281	7.03	315	7.77	155	7.88	454	0.56	1398.32	<0.001	0.1306	169	427
2008	46,674	49,873	309	6.62	379	7.60	202	9.05	486	0.52	2243.70	<0.001	0.1507	208	480
2009	42,301	56,620	344	8.13	480	8.48	234	10.59	590	0.61	2604.21	<0.001	0.1602	264	560
2010	47,968	58,854	444	9.26	473	8.04	272	11.03	645	0.62	3067.23	<0.001	0.1671	313	604
2011	48,360	65,614	384	7.94	526	8.02	298	13.32	612	0.55	4515.66	<0.001	0.1952	366	544
Total	39,0583	442,380	2954	7.56	3587	8.11	1944	10.39	4599	0.57	22660.94	<0.001	0.1627	2200	4341

LBW: Low birth weight.