Table 4.

Linear regression analysis examining the relation of log blood lead levels and covariates both in univariate and multivariate models

Independent variable	Plasma lead concentration				Whole blood concentration
	Univariate model		Multivariate model		Univariate model		Multivariate model
	β	p value	β	p value	β	p value	β	p value
Number of cigarettes/day	0.337	<0.001	0.238	0.014	0.359	<0.001	0.177	0.054
Duration of smoking before conception (year)	0.269	<0.001	0.142	0.061	0.409	<0.001	0.297	<0.001
Cotinine level	0.291	<0.001	0.051	0.600	0.344	<0.001	0.075	0.424