Table 6.

Cognitive development of children with blood lead levels below 5 μg/dl over the follow-up in the GEE models (1,240 measurements)

MDI (12–36 months)	β	SE	z	p	95% CI
Maternal education1	1.265	0.315	4.02	0.000	0.649 to 1.882
Birth order	−1.335	0.653	−2.04	0.041	−2.615 to–0.055
Prenatal ETS2	−0.185	0.099	−1.87	0.061	−0.379 to 0.009
Gender of child3	4.332	0.790	5.49	0.000	2.785 to 5.880
Cord blood lead level4	−6.618	2.499	−2.65	0.008	−11.517 to–1.719

¹Primary school only = 0; medium or high school = 1; university degree or uncompleted university = 2.

²No exposure = 0; 1–10 cigarettes smoked daily at home = 1, >10 cigarettes smoked daily at home = 2.

³Boys = 0, girls = 1.

⁴log transformed.