Table 3.

Adjusted mean and difference in BMI by change in prenatal tobacco smoke exposure^*

Self-Reported Prenatal Tobacco Smoke Category	N†	Birth, N=293 (SD) [95% CI]	4-Week, N=297 (SD) [95% CI]	1 Year, N=266 (SD) [95% CI]	2 Year, N=229 (SD) [95% CI]	3 Years, N=202 (SD) [95% CI]
Mean among unexposed	214	13.0 (1.5)	14.7 (1.4)	16.9 (1.6)	16.6 (1.3)	15.9 (1.3)
SHS	43	0.0 [−0.4, 0.5]	0.0 [−0.4, 0.4]	−0.1 [−0.7, 0.4]	−0.1 [−0.6, 0.5]	0.0 [−0.5, 0.6]
Active	36	0.3 [−0.2, 0.8]	0.3 [−0.2, 0.8]	0.2 [−0.4, 0.8]	0.6 [0.0, 1.2]	1.1 [0.4, 1.7]
Categorical Prenatal Serum Cotinine Concentrations	N†	Birth, N=300 (SD) [95% CI]	4-Week, N=303 (SD) [95% CI]	1 Year, N=273 (SD) [95% CI]	2 Years, N=236 (SD) [95% CI]	3 Years, N=209 (SD) [95% CI]
Mean among unexposed (<0.015 ng/mL)	116	13.2 (1.4)	14.9 (1.3)	17.0 (1.7)	16.4 (1.2)	15.7 (1.2)
SHS (0.015–3 ng/mL)	153	−0.2 [−0.5, 0.2]	−0.2 [−0.5, 0.1]	−0.1 [−0.6, 0.3]	0.3 [−0.1, 0.7]	0.4 [0, 0.8]
Active (>3 ng/mL)	31	0.0 [−0.6, 0.6]	0.1 [−0.5, 0.6]	0.4 [−0.4, 1.1]	0.6 [−0.1, 1.4]	1.0 [0.3, 1.8]
Continuous Prenatal Serum Cotinine Concentrations
Log10-transformed mean cotinine	300	0.0 [−0.2, 0.2]	0.0 [−0.2, 0.2]	0.1 [−0.1, 0.3]	0.2 [0.0, 0.4]	0.3 [0.1, 0.5]
Log10-transformed mean cotinine (SHS exposed only)‡	269	−0.1 [−0.4, 0.2]	−0.2 [−0.5, 0.1]	−0.2 [−0.6, 0.2]	0.2 [−0.2, 0.5]	0.3 [−0.1, 0.6]

^*-Adjusted for child age (in years), child age squared, child age cubed, maternal age (<25, 25–34, and >34 years), education (<12, 12, and >12 years), race (non-Hispanic white, non-Hispanic black, and other), marital status (married and non-married), depression at baseline home visit (moderately or severely depressed and mildly or minimally depressed), breast feeding duration since last visit (years), parity (0, 1, and >1), income ($10,000 increments), and maternal BMI (kg/m²) at 16 weeks gestation.

^†-Sample size at birth

^‡-Women could not have cotinine concentration > 3 ng/mL in any serum measurement. SHS-Secondhand smoke