Table 4

Adjusted odds ratios (OR) and 95% confidence intervals (CI) of having sought medical care due to allergic symptoms during the last year by presence of secondhand tobacco smoke early in life and presence of parental allergy in 4-year old children, Malmö, Sweden

No parent with an allergy

At least one parent with an allergy

Secondhand tobacco smoke at 0-4 weeks of age*

Secondhand tobacco smoke at 0-4 weeks of age*

No

Yes

No

Yes

OR; 95% CI*

OR; 95% CI

OR; 95% CI

OR; 95% CI

1.00†

0.97 (0.53, 1.77)§

2.26 (1.61, 3.18)§

3.77 (2.20, 6.44)§

Secondhand tobacco smoke at 8 months of age*

Secondhand tobacco smoke at 8 months of age*

No

Yes

No

Yes

OR; 95% CI*

OR; 95% CI

OR; 95% CI

OR; 95% CI

1.00†

1.04 (0.58, 1.86)§

2.02 (1.42, 2.87)§

4.46 (2.68, 6.44)§¶

* OR, odds ratio; CI, confience interval; Secondhand tobacco smoke at 0-4 weeks and 8 months were categorized into no (no secondhand tobacco smoke at all) and yes (daily secondhand tobacco smoke, including smoking outside).

† Reference level.

‡ Presence of allergy was assessed by the question if the child had sought medical care during the last 12 months, due to atopic eczema, food allergies or asthma.

§ Adjusted for sex, year, maternal smoking during pregnancy, maternal educational level, parents'country of birth, taken part of parental education program, and having a pet.

¶ Statistically significantly different (p < 0.05) from the category: At least one parent with an allergy and no secondhand tobacco smoke.

Hansen et al. BMC Pediatrics 2010 10:61   doi:10.1186/1471-2431-10-61