Fig. 2

HRs/ORs (95% CIs) of type 1 diabetes for maternal smoking versus non-smoking during pregnancy in different study designs. HR, hazard ratio; OR, odds ratio; CI, confidence interval. Model 1 was adjusted for sex and year of birth. The model in the cohort analysis was fitted with a frailty component to take into account the non-independence among children born by the same mother. The model in the cousin (or sibling) analysis was conditioning on cousin (or sibling) groups. Model 2 was additionally adjusted for maternal education, paternal education, maternal age at delivery, maternal body mass index during pregnancy, maternal diabetes, paternal diabetes, and birth order on the basis of model 1. Model 3 was additionally adjusted for gestational age and birth weight for gestational age on the basis of model 2