Table 3.

Association of Maternal Folic Acid Supplement Use and Specific Neural Tube Defects Stratified by Race/Ethnicity, National Birth Defects Prevention Study, 1998–2003

	Controls		Anencephaly				Spina Bifida
	No.	%	No.	%	Crude Odds Ratio	95% Confidence Interval	No.	%	Crude Odds Ratio	95% Confidence Interval
White, non-Hispanic
Nonusers, B3–P1	773	35.6	24	28.9	Referent	Referent	59	30.9	Referent	Referent
Users, B3–P1	789	36.3	30	36.1	1.2	0.7, 2.1	79	41.3	1.3	0.9, 1.9
P1 initiator	611	28.1	29	34.9	1.5	0.9, 2.6	53	27.8	1.1	0.8, 1.7
Black, non-Hispanic
Nonusers, B3–P1	273	63.3	6	33.3	Referent	Referent	28	66.7	Referent	Referent
Users, B3–P1	64	14.9	4	22.2	2.8	0.8, 10.4	8	19.0	1.2	0.5, 2.8
P1 initiator	94	21.8	8	44.4	3.9	1.3, 11.5	6	14.3	0.6	0.3, 1.6
Hispanic
Nonusers, B3–P1	617	71.3	45	67.2	Referent	Referent	93	69.4	Referent	Referent
Users, B3–P1	62	7.2	3	4.5	0.7	0.2, 2.2	4	3.0	0.4	0.2, 1.2
P1 initiator	186	21.5	19	28.4	1.4	0.8, 2.5	37	27.6	1.3	0.9, 2.0

Abbreviations: B3, 3 months before pregnancy; P1, first month of pregnancy.