Table 3.

Estimated Risk of Lung Cancer Among Women by Parity and Smoking History (n = 1,852), Lung Cancer Susceptibility Study, Boston, Massachusetts, 1992–2004^a

Parity	Never Smokers (n = 434)						Ever Smokers (n = 1,418)
	Cases		Controls		AORb	95% CI	Cases		Controls		AORb	95% CI
	No.	%	No.	%			No.	%	No.	%
0 (nulliparous)	21	21	50	15	1	Referent	128	14	67	13	1	Referent
≥1	81	79	282	85	0.46	0.25, 0.85	774	86	449	87	0.82	0.58, 1.17

Abbreviations: AOR, adjusted odds ratio; CI, confidence interval.

^aP = 0.12 in a likelihood ratio test comparing the multivariate model containing an interaction term with the same model without the interaction term.

^bAdjusted for age, smoking status, pack-years of smoking, and years since quitting smoking. Stratum-specific odds ratios were directly estimated in the full data set of 1,852 women.