Table 1 Selected characteristics of study population and associations with early wheezing (n = 514)
No (%)Early wheezing
Unadjusted OR (95% CI)
Gender of baby
    Boy255 (49.6)1.0
    Girl259 (50.4)0.7 (0.4 to 1.4)
Maternal country of birth
    USA69 (13.5)1.0
    Mexico433 (84.4)0.6 (0.2 to 1.4)
    Other11 (2.1)0.9 (0.1 to 8.0)
Family income
    Above poverty level171 (33.3)1.0
    At or below poverty level343 (66.7)2.5 (1.0 to 6.2)*
Family history of asthma
    No417 (82.3)1.0
    Yes90 (17.8)1.4 (0.6 to 3.2)
Breastfeeding duration
    Never breastfed28 (5.5)1.0
    ⩽6 months272 (53.5)1.2 (0.3 to 5.4)
    >6 months208 (40.9)0.7 (0.1 to 3.2)
Maternal smoking during pregnancy
    No483 (94.2)1.0
    Yes30 (5.9)1.6 (0.5 to 5.4)
Child exposed to tobacco smoke (0–12 months)
    No431 (92.1)1.0
    Yes37 (7.9)3.0 (1.2 to 7.9)*
Signs of cockroaches in home (0–12 months)
    No140 (33.5)1.0
    Yes278 (66.5)0.9 (0.4 to 1.9)
Signs of rodents in home (0–12 months)
    No251 (60.1)1.0
    Yes167 (40.0)1.8 (0.9 to 3.8)
Moderate to severe visible mould in home (0–12 months)
    No148 (35.4)1.0
    Yes270 (64.6)0.8 (0.4 to 1.7)
Any wall >17% moisture (6 months)
    No273 (72.4)1.0
    Yes104 (27.6)0.3 (0.1 to 1.0)*
Gas stove in home (0–12 months)
    No91 (19.4)1.0
    Yes377 (80.6)3.8 (0.9 to 16.4)
Any pets (0–12 months)
    No302 (67.0)1.0
    Yes149 (33.0)1.9 (0.9 to 3.9)
Diagnosis of lower respiratory infection (0–12 months)†
    No350 (68.1)1.0
    Yes164 (31.9)4.0 (2.0 to 8.2)*
Mean daily PM2.5 in first 3 months of life
    < 8 μg/m3230 (44.8)1.0
    8–12 μg/m3218 (42.4)1.7 (0.8 to 3.7)
    ⩾12 μg/m366 (12.8)2.4 (0.9 to 6.4)
Season of birth
    Low spore/low pollen203 (22.0)1.0
    Spore195 (37.9)2.8 (1.2 to 6.5)*
    Pollen116 (22.6)1.6 (0.6 to 4.4)

  • *p<0.05.

  • †Diagnosis of bronchitis, bronchiolitis, pneumonia or croup noted in medical records.

  • CI, confidence interval; OR, odds ratio; PM2.5, particulate matter with aerodynamic diameter ⩽2.5 μm.