. Author manuscript; available in PMC: 2015 Jul 9.

Published in final edited form as: Occup Environ Med. 2014 Jun 3;71(8):529–535. doi: 10.1136/oemed-2013-101833

Table 2.

Association between maternal occupational exposure to polycyclic aromatic hydrocarbons (PAHs) and small for gestational age (SGA) offspring, National Birth Defects Prevention Study, 1997–2002

	Crude analysis				Adjusted analysis^*
	SGA n	Not SGA n	OR	95% CI	SGA n	Not SGA n	OR	95% CI
Dichotomous Exposure
No PAH exposure	204	2480	1.0	(Reference)	204	2480	1.0	(Reference)
Any PAH exposure	17	102	2.0	(1.2 to 3.5)	17	102	2.2	(1.3 to 3.8)
Cumulative Exposure^†^‡
No PAH exposure (0)	204	2480	1.0	(Reference)	204	2480	1.0	(Reference)
Low PAH exposure (8–205)	9	50	2.2	(1.1 to 4.5)	9	50	2.5	(1.2 to 5.3)
High PAH exposure (206–3086)	8	52	1.9	(0.9 to 4.0)	8	52	1.9	(0.9 to 4.2)

Adjusted for maternal age.

^†

Cumulative exposure (unit-hours) was estimated by: (weighted intensity in μg/m³/h)×((exposure frequency in hrs/week)/(40 h/week))×((hours worked per week)/(7 days per week))×(number of days worked from 1 month before conception to delivery).

^‡

Cumulative exposure measured in μg/m³-h.