Table 2. Factors associated with smoking before pregnancy and quitting during pregnancy of the study population in the Greek RHEA birth cohort study, 2007–2008.

		ORa	95% CI	P valueb
Factors associated with smoking before pregnancy (Current/ex-smokers vs. nonsmokers)
Paternal age	Change per year	0.96	0.95–0.97	<0.001
Paternal ethnicity	Greek	1.00
	Non-Greek	0.41	0.23–0.74	0.003
Education level	High	1.00
	Mid/low	1.40	1.06–1.85	0.018
Residence	Urban	1.00
	Rural	0.68	0.49–0.92	0.013
Paternal smoking status	Nonsmoker	1.00
	Smoker	2.90	2.25–3.75	<0.001
Factors associated with continued smoking during pregnancy (Current vs. ex-smokers)
Paternal age	Change per year	0.98	0.97–0.99	0.002
Paternal ethnicity	Greek	1.00
	Non-Greek	3.03	0.95–9.70	0.062
Paternal smoking status	Nonsmoker	1.00
	Smoker	1.76	1.16–2.67	0.008
Parity	Primipara	1.00
	Multipara	1.72	1.13–2.61	0.011

^aBackward logistic regression analysis was conducted with the following factors in step 1: maternal and paternal age, level of education (high vs. mid/low), ethnicity (Greek vs. immigrant), paternal smoking status, parity (primipara vs. multipara), place of residence (urban vs. rural), and maternal occupational status (working vs. unemployed or on leave). In the first regression analysis an OR >1 indicates women more likely to be smokers; in the second regression analysis, an OR >1 indicates women who continued to smoke during pregnancy and did not quit.

^bP values based on 2-sided tests, with variables excluded when P > 0.1. Statistical significance was defined as P < 0.05.