Table 2.

The proportions of incidences and relative factors of CHD in Xi’an city from 2003 to 2012

Year	Urban		Rural		χ2	P	Contingency coefficient	CHD with LBW		CHD with normal birth weight		χ2	P	Contingency coefficient	Prenatal diagnosis (n)	Postpartum diagnosis (n)
	n	Incidence (%)	n	Incidence (%)				n	Incidence (%)	n	Incidence (%)
2003	11	0.49	5	0.28	1.50	0.220	0.0060	2	1.98	14	0.34	3.35	0.067	0.0129	3	13
2004	8	0.32	5	0.25	0.39	0.534	0.0028	4	3.60	9	0.19	35.11	<0.001	0.0311	4	9
2005	11	0.41	3	0.12	4.52	0.033	0.0091	2	1.40	12	0.22	3.62	0.057	0.0117	4	10
2006	17	0.59	13	0.48	0.66	0.415	0.0034	3	1.74	27	0.47	3.06	0.080	0.0095	5	25
2007	22	0.55	16	0.43	1.03	0.310	0.0036	13	6.61	25	0.32	146.84	<0.001	0.0445	12	26
2008	19	0.41	17	0.37	0.28	0.594	0.0017	10	4.48	26	0.28	91.95	<0.001	0.0326	13	23
2009	32	0.76	28	0.51	2.74	0.098	0.0053	19	8.60	41	0.42	222.80	<0.001	0.0488	24	36
2010	73	1.52	51	0.88	9.76	0.002	0.0096	48	19.46	76	0.73	698.88	<0.001	0.0815	59	65
2011	40	0.83	47	0.73	0.45	0.503	0.0020	42	18.77	45	0.40	928.32	<0.001	0.0910	56	31
2012	79	1.30	75	1.05	1.75	0.185	0.0036	69	29.68	85	0.66	1577.23	<0.001	0.1094	76	78
Total	312	0.80	260	0.62	13.45	<0.001	0.0040	212	1133	360	0.44	3122.86	<0.001	0.0611	256	316

CHD: Congenital heart disease; LBW: Low birth weight.