Table 4 Exposure to parental cigarette smoking at 2 months and sensitisation (IgE ⩾0.35 kU_A/l) to any inhalant and/or food allergen at 4 years of age

	N	n	Crude model OR (95% CI)	Adjusted for parental allergy and socioeconomic status OR (95% CI)	Additional adjustment for maternal smoking during pregnancy OR (95% CI)
No parent smokes	1970	420	1.00 (Referent)	1.00 (Referent)	1.00 (Referent)
Only one parent smokes (⩾1 cigarette a day)	408	99	1.19 (0.93 to 1.53)	1.19 (0.92 to 1.54)	1.21 (0.93 to 1.59)
Both parents smoke (one or both less than 10 cig a day)	59	17	1.54 (0.87 to 2.73)	1.68 (0.94 to 2.99)	1.79 (0.94 to 3.38)
Both parents smoke ⩾10 cig a day	31	11	1.82 (0.88 to 3.76)	1.84 (0.89 to 3.84)	1.99 (0.89 to 4.45)
			p_trend = 0.015	p_trend = 0.011	p_trend = 0.019

N, total number in the group; n, number exposed.