Table 3. The distribution NVP in the case and control groups for different subtypes of NTDs.

	Anencephaly			Spina bifida			Encephalocele
Factor	Case	Control	P	Case	Control	P	Case	Control	P
NVP
Light	114	135	0.013	121	136	0.294	38	47	0.064*
Moderate	58	51		57	46		18	16
Severe	22	8		22	18		9	2
Intake of folic acid supplements#
Light NVP	38	65	0.590	43	66	0.742	16	24	0.625*
Moderate NVP	13	33		16	22		6	9
Severe NVP	2	4		7	7		1	0
Non-intake of folic acid supplements#
Light NVP	76	70	0.002	78	70	0.367	22	23	0.170*
Moderate NVP	45	18		41	24		12	7
Severe NVP	2	4		15	11		8	2

*: The P value was calculated by Fisher exact test.