Table 2.

Association Between Exposure to Nitrosatable Drugs Around the Time of Conception^a and Neural Tube Defects, National Birth Defects Prevention Study, 1997–2005

Defect Group and Type of Drug Exposure	Cases		Controls		Unadjusted ORb	95% CI	Adjusted ORc	95% CI
	No.	%	No.	%
Any neural tube defect
No nitrosatable drug exposure	940	80.5	5,445	83.1	1	Referent	1	Referent
Secondary amines	125	11.7	646	10.6	1.12	0.91, 1.37	1.22	0.99, 1.50
Tertiary amines	141	13.0	570	9.5	1.43	1.18, 1.75	1.60	1.31, 1.95
Amides	64	6.4	340	5.9	1.09	0.83, 1.44	1.21	0.92, 1.61
Anencephalyd
No nitrosatable drug exposure	263	79.0	5,445	83.1	1	Referent	1	Referent
Secondary amines	39	12.9	646	10.6	1.25	0.88, 1.77	1.41	0.99, 2.01
Tertiary amines	46	14.9	570	9.5	1.67	1.21, 2.31	1.96	1.40, 2.73
Amides	14	5.1	340	5.9	0.85	0.49, 1.48	0.98	0.56, 1.71
Spina bifida
No nitrosatable drug exposure	569	81.4	5,445	83.1	1	Referent	1	Referent
Secondary amines	69	10.8	646	10.6	1.02	0.79, 1.33	1.08	0.83, 1.42
Tertiary amines	81	12.5	570	9.5	1.36	1.06, 1.74	1.48	1.15, 1.91
Amides	40	6.6	340	5.9	1.13	0.80, 1.58	1.23	0.87, 1.73
Encephalocele
No nitrosatable drug exposure	108	79.4	5,445	83.1	1	Referent	1	Referent
Secondary amines	17	13.6	646	10.6	1.33	0.79, 2.23	1.54	0.90, 2.62
Tertiary amines	14	11.5	570	9.5	1.24	0.71, 2.18	1.48	0.83, 2.63
Amides	10	8.5	340	5.9	1.48	0.77, 2.86	1.76	0.90, 3.44

Abbreviations: CI, confidence interval; OR, odds ratio.

^aThe period from 1 month before conception to 1 month after conception.

^bCrude and adjusted odds ratios included only cases and controls for whom we had complete information on drug exposures and covariates.

^cAdjusted for maternal race/ethnicity, educational level, and folic acid supplementation around the time of conception.

^dThis category included craniorachischisis.