Table 3.

Mean difference (95% CI) in birth measurements of children born to smoking mothers, comparing those where the child's grandmother had smoked with those who had not

	MGM+M+ vs MGM−M+		PGM+M+ vs PGM−M+
	Unadjusted	Adjusted*	Unadjusted	Adjusted*
Total IQ
Boys	−3.87	−2.45	−4.00	−2.90
95% CI	(−6.34 to −1.40)	(−4.96 to +0.07)	(−6.92 to −1.08)	(−5.72 to −0.08)
p Value	0.002	0.057	0.007	0.044
Number	694	612	507	482
Girls	−2.50	−0.40	−3.03	−1.36
95% CI	(−4.90 to −0.11)	(−2.85 to +2.05)	(−5.78 to −0.28)	(−4.07 to +1.36)
p Value	0.041	0.749	0.031	0.327
Number	617	551	456	436
Performance IQ
Boys	−2.64	−1.48	−2.44	−1.40
95% CI	(−5.20 to −0.08)	(−4.20 to +1.24)	(−5.40 to +0.50)	(−4.39 to +1.60)
p Value	0.043	0.287	0.104	0.360
Number	698	616	510	485
Girls	−2.46	−0.50	−3.03	−1.74
95% CI	(−5.01 to +0.09)	(−3.19 to +2.19)	(−5.88 to −0.18)	(−4.69 to +1.20)
p Value	0.059	0.716	0.037	0.245
N	619	552	457	436
Verbal IQ
Boys	−3.75	−2.40	−4.73	−3.65
95% CI	(−6.30 to −1.21)	(−5.00 to +1.20)	(−7.81 to −1.66)	(−6.60 to −0.70)
p Value	0.004	0.070	0.003	0.015
Number	697	615	509	484
Girls	−1.98	−0.15	−2.48	−0.81
95% CI	(−4.37 to +0.42)	(−2.60 to +2.30)	(−5.28 to +0.32)	(−3.54 to +1.92)
p Value	0.106	0.906	0.082	0.561
Number	617	551	456	436

Values in italics indicate a significance of p<0.05. *Adjusted for maternal education, parity, partner smoked in pregnancy, gestational length at birth of study child and the amount the mother smoked.

M, mother; MGM, maternal grandmother; PGM, paternal grandmother.