Crude and adjusted odds ratios (OR) for ALL comparing children with older siblings to children without older sibling, stratified by age groups.

a<p>univariable conditional logistic regression model.</p>b<p>175 cases, 1382 controls.</p>c<p>130 cases, 1032 controls.</p>d<p>120 cases, 936 controls.</p>e<p>p values for trend were obtained including the variable continuously; the coding for number of older siblings was 0, 1, 2.</p>f<p>multivariable conditional logistic regression adjusted for maternal age, paternal age and socio-economic status.