Table 3.

Association of Maternal Occupational Exposure to Polycyclic Aromatic Hydrocarbons and the Risk of Any Neural Tube Defect or Specific Birth Defect in Offspring, National Birth Defects Prevention Study, 1997–2002

	Controls	Any Neural Tube Defect		Anencephaly		Spina Bifida		Encephalocele
Exposure to Occupational PAHs	n	n	OR (95% CI)	n	OR (95% CI)	n	OR (95% CI)	n	OR
Not exposed (referent)	2883	494	1.00	131	1.00	302	1.00	61	1.00
Exposed (crude)	106	26	1.43 (0.92–2.22)	5	1.04 (0.42–2.59)	19	1.71 (1.03–2.83)	2	n/aa
Exposed (adjusted, most parsimonious model)	103	22	1.01 (0.61–1.66)b	4	n/a	17	1.21 (0.69–2.11)c	1	n/a
Exposed (adjusted for all smoking exposure)	106	25	1.26 (0.80–1.97)d	4	n/a	19	1.55 (0.93–2.58)d	1	n/a
Exposed (adjusted for all smoking exposure and other covariates in original parsimonious model)	103	22	1.00 (0.62–1.62)e	4	n/a	17	1.20 (0.69–2.06)f	1	n/a

^aNot available; the number of exposed cases was too low for meaningful analysis.

^bAdjusted for BMI, secondhand smoking at home, study center.

^cAdjusted for BMI and education.

^dAdjusted for smoking, secondhand smoking at home, and secondhand smoking at work.

^eAdjusted for smoking, secondhand smoking at home, secondhand smoking at work, BMI, and study center.

^fAdjusted for smoking, secondhand smoking at home, secondhand smoking at work, BMI, and education.

PAH, polycyclic aromatic hydrocarbon; OR, odds ratio; CI, confidence interval; BMI, body mass index.