Cigarette smoking and CD location according to the Montreal Classification.

<p>Cigarette smoking and CD location according to the Montreal Classification.</p

Cigarette smoking and complicated CD.

<p>Cigarette smoking and complicated CD.</p

Demographic and baseline characteristics of participants.

<p>Demographic and baseline characteristics of participants.</p

Score analysis for environmental exposures during 3 age intervals; Group A.

<p>Score analysis for environmental exposures during 3 age intervals; Group A.</p

Score analysis for environmental risk factors during the 3 age intervals.

<p>Score analysis for environmental risk factors during the 3 age intervals.</p

Environmental risk factors over three age intervals; 0–5 years, 6–10 years and 11–18 years. [4].

<p>Environmental risk factors over three age intervals; 0–5 years, 6–10 years and 11–18 years. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0171742#pone.0171742.ref004" target="_blank">4</a>].</p