Covariates
Multiple potentially confounding variables were assessed to correct for
biases in the statistical analysis:
- basic characteristics: age at baseline, age at follow-up, sex
- information about the pre-natal phase: smoking during pregnancy and
passive smoking during pregnancy
- information about the post-natal phase: the location of residency in
the first six months (farm, rural village, small town/large
village, suburb or large city, inner city, do not remember, unknown ),
exposure to a furry/hairy pet in the first six months, whether the
infant was breast-fed and the duration of breastfeeding (not
breast-fed, up to 3 months, more than 3 months, breastfed but do not
remember duration, do not know if breast-fed )
- parental characteristics: asthma presence among parents, their income
level /month (no information on income, < 1500
\euro, 1500 – 3000 \euro, > 3000 \euro ) and their
education level (low, medium, high, other/unknown )