Effects of Tobacco Smoking in Pregnancy on Offspring Intelligence at the Age of 5

Table 2

Maternal smoking in pregnancy and WPPSI-R^a performance.

Average number of cigarettes/day	Crude		Adjusted for core confounders^b	Adjusted for potential confounders^c
	Mean score	Mean difference (95% CI)	Mean difference (95% CI)	Mean difference (95% CI)
Full-scale IQ
0	106.1	Reference	Reference	Reference
1–9	103.3	−2.8 (−5.5, −0.1)	−1.0 (−3.4, 1.4)	−0.9 (−3.6, 1.8)
10+	102.5	−3.6 (−6.1, −1.2)	−1.0 (−3.3, 1.4)	−0.3 (−3.1, 2.5)
Verbal IQ
0	105.3	Reference	Reference	Reference
1–9	103.2	−2.1 (−4.4, 0.2)	−0.5 (−2.6, 1.6)	−0.6 (−2.8, 1.7)
10+	102.8	−2.5 (−4.7, −0.4)	−0.1 (−2.2, 2.0)	0.2 (−2.1, 2.8)
Performance IQ
0	105.6	Reference	Reference	Reference
1–9	102.6	−3.0 (−6.4, 0.5)	−1.4 (−4.5, 1.7)	−1.0 (−4.7, 2.7)
10+	101.5	−4.1 (−7.1, −0.9)	−1.7 (−4.6, 1.2)	−1.0 (−4.6, 2.6)

^aWechsler Preschool and Primary Scale of Intelligence-Revised.
^bParental education, maternal IQ, prenatal maternal alcohol consumption, the child’s sex, age at testing, and tester.
^cParental education, maternal IQ, prenatal maternal alcohol consumption, the child’s sex, age at testing, and tester, maternal age, parity, maternal marital status, prenatal paternal smoking, postnatal parental smoking, breast feeding, maternal prepregnancy BMI, the child’s sex, age at testing, health status, family/home environment.