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Table 1 Characteristics of a cohort of children and their families by exposure to maternal daily smoking of one cigarette or more during pregnancy

From: Maternal smoking during pregnancy increases the risk of recurrent wheezing during the first years of life (BAMSE)

  No foetal exposure Foetal exposure to tobacco smoking
  n/N1 % 95% CI n/N1 % 95% CI p-value2
Gender (male) 1676/3321 51 49 – 52 242/469 52 47 – 56 0.646
Parental asthma 533/3302 16 15 – 17 73/457 16 13 – 19 0.927
Birth weight <2500 g 121/3321 3.6 3.0 – 4.3 19/469 4.1 2.5 – 6.3 0.661
Gestational age <36 w 102/3321 3.1 2.5 – 3.7 15/469 3.2 1.8 – 5.2 0.946
Exclusive breastfeeding ≥4 months 2690/3316 81 80 – 82 323/469 69 65 – 73 <0.001
Maternal age ≥26 years 3091/3320 93 92 – 94 413/469 88 85 – 95 <0.001
Socioeconomic index (SEI)3        
1) Blue-collar 482/3311 15 13 – 16 140/468 30 26 – 34 <0.001
2) White collar 2792/3311 84 83 – 86 323/468 69 62 – 71 <0.001
3) Others4 37/3311 1.1 0.8 – 1.5 5/468 1.1 0.1 – 2.0 0.924
Keeping of cat and/or dog 426/3321 13 12 – 14 121/469 26 22 – 30 <0.001
Signs of dampness5 267/3309 8.1 7.1 – 9.0 39/468 8.3 5.8 – 11 0.844
Construction year of the home >1961 1679/3319 49 48 – 51 266/468 57 52 – 61 0.003
  1. 1 The numbers do not add up because of missing data.
  2. 2 Pearson chi-square test.
  3. 3 Socioeconomic status of the parents according to socioeconomic index measured by the Nordic standard occupational classification (NYK) and Swedish socioeconomic classification (SEI).
  4. 4 Student, unemployed etc.
  5. 5Smell or visible signs of mould in the dwelling and/or water damage inside construction.