Table 1

IRR and 95% CI of T1DM among children and young adults (aged 0–18 years) born in Sweden between years 1992 and 2004 and followed until 2009 by maternal duration of residence in Sweden before the child’s birth and parental country of birth

IRR* (95% CI)IRR** (95% CI)
Duration of residence of mothers before child’s birthDuration of residence of mothers before child’s birth
0–5 years6–10 years≥11 yearsSwedes0–5 years6–10 years≥11 yearsSwedes
Parental migration status
 Foreign born vs. Swedes0.54 (0.47–0.63)0.69 (0.56–0.84)0.71 (0.61–0.83)10.55 (0.48–0.64)0.69 (0.57–0.85)0.71 (0.62–0.83)1
 Foreign born††0.77 (0.62–0.94)0.98 (0.76–1.25)10.78 (0.63–0.96)0.96 (0.75–1.24)1
 East African vs. Swedes1.03 (0.72–1.46)1.39 (0.86–2.24)2.34 (1.30–4.24)11.00 (0.70–1.42)1.32 (0.82–2.14)2.27 (1.25–4.10)1
 East African††0.36 (0.17–0.75)0.48 (0.21–1.09)10.39 (0.17–0.86)0.49 (0.21–1.12)1
 Other Nordic vs. Sweden0.85 (0.54–1.33)1.11 (0.69–1.78)1.07 (0.87–1.32)10.88 (0.56–1.38)1.13 (0.70–1.81)1.08 (0.88–1.33)1
 Other Nordic††1.11 (0.43–2.86)1.34 (0.44–4.04)10.94 (0.34–2.55)1.22 (0.40–3.75)1
  • The study base comprised 1,263,358 individuals. Exclusions: infants delivered before 28th or after 43rd completed weeks of gestation, from multiple births, with any congenital malformation, individuals with missing data on gestational age, missing data on birth weight, infants with a birth weight ± 6 standard deviations from the mean, records with missing or extreme data on maternal height, weight, and age, and women with invalid immigration. The final cohort comprised 984,798 eligible individuals.

  • * Adjusted for child’s age at follow-up.

  • ** Adjusted for maternal age, maternal BMI, smoking at enrollment, parental education, parity, preeclampsia, and child’s sex and age at follow-up.

  • Swedes as a reference.

  • †† Longest duration of stay as a reference.