Table 3.

Associations between prenatal and postnatal average carbon monoxide (CO) and assignment to the lowest $z$-score trajectory.

Trajectory measurementa	$N$	Bivariate model				$N$	Multivariable modelb
		Prenatal		Postnatal			Prenatal		Postnatal
		$\text{OR}$ (95% CI)	$p$-Value	$\text{OR}$ (95% CI)	$p$-Value		$\text{OR}$ (95% CI)	$p$-Value	$\text{OR}$ (95% CI)	$p$-Value
Weight-for-length $z$-score	1,127	1.06 (0.88, 1.28)	0.55	1.02 (0.91, 1.14)	0.76	1,125	1.06 (0.87, 1.28)	0.56	1.03 (0.94, 1.13)	0.47
Length-for-age $z$-score	1,127	1.22 (1.06, 1.41)	$<0.01$	0.95 (0.83, 1.09)	0.47	1,125	1.25 (1.08, 1.45)	$<0.01$	0.98 (0.84, 1.14)	0.75
Weight-for-age $z$-score	1,130	0.98 (0.83, 1.15)	0.76	0.99 (0.90, 1.08)	0.79	1,128	0.99 (0.84, 1.17)	0.93	1.00 (0.92, 1.10)	0.92

Note: Per 1-ppm increase in average CO exposure, all effects determined with cluster-robust standard errors. The lowest weight-for-length, length-for-age, and weight-for age $z$-score trajectories were at or below $-2$ at each time point, consistent with commonly used definitions of wasted, stunted, and underweight, respectively. Analyses are logistic regression where ORs may be interpreted as the odds of being in the lowest $z$-score trajectory as compared with others per 1-ppm increase in average CO exposure, respectively. CI, confidence interval; OR, odds ratio.

^a All trajectories include four groups.

^b Multivariable models include both prenatal and postnatal average CO exposure and adjust for child sex, maternal age, ethnicity, and wealth index.