Table 6.

Results for estimation of Generalized Additive Model (GAM) to birth outcomes, adjusted for birth order

Variables	Parameter estimates		Analysis of deviance
	Estimate	Standard error	Chi-square	p
Birthweight
Paternal smoking amount	−2.097	0.900	30.09	<0.001
Maternal smoking amount	−16.454	3.732	6.14	0.105
Smoking amount in both parents	−2.890	0.890	27.67	<0.001
Gestational age
Paternal smoking amount	−0.010	0.004	22.67	<0.001
Maternal smoking amount	−0.062	0.014	11.14	0.011
Smoking amount in both parents	−0.013	0.004	16.87	0.001
Low birthweight
Paternal smoking amount	0.017	0.006	17.75	<0.001
Maternal smoking amount	0.070	0.019	1.18	0.554
Smoking amount in both parents	0.022	0.006	12.23	0.002
Preterm birth
Paternal smoking amount	0.021	0.007	16.07	<0.001
Maternal smoking amount	0.088	0.019	6.55	0.038
Smoking amount in both parents	0.028	0.007	10.45	0.005