Table 1.

Descriptive statistics of serum cotinine concentrations (ng/mL) at birth and at 12, 24, 36 and 48 months: N, range, quartiles and geometric mean with 95% CI

	N	Range	Quartiles			Geometric mean
			P25	P50	P75	Mean	95% CI
Newborn’s cotinine*	280	0.00000–261.0	0.003	0.017	0.088	0.022	0.015 to 0.032
Child’s cotinine*
12 months	270	0.00030–35.3	0.023	0.063	0.357	0.093	0.073 to 0.118
24 months	197	0.00126–10.5	0.020	0.046	0.212	0.070	0.053 to 0.092
36 months	196	0.00032–21.6	0.012	0.033	0.199	0.046	0.034 to 0.064
48 months	150	0.00024–14.9	0.013	0.027	0.249	0.047	0.033 to 0.067

*Analysis is restricted to participants with both maternal-reported data and cotinine measures.

N, number of observations; P, percentile.