Table 1

Characteristics of case subjects with childhood T1D and randomly selected control subjects in MoBa

Control subjects (n = 576)Case subjects (n = 189)
Age at end of follow-up (years)*11.7 (7.7–17.1)12.7 (8.0–16.6)
Female sex285 (49.5)93 (49.2)
Maternal T1D0 (0.0)7 (3.7)
Preterm birth19 (3.3)10 (5.3)
 Missing data1 (0.2)1 (0.5)
Birth weight (g)
 <2,5008 (1.4)7 (3.7)
 2,500–4,500539 (93.6)174 (92.1)
 >4,50029 (5.0)8 (4.2)
Parity
 No previous births248 (43.1)93 (49.2)
 One birth215 (37.3)57 (30.2)
 Two or more births113 (19.6)39 (20.6)
Maternal age (years)30 (17–42)30 (19–42)
Maternal non-Norwegian ethnicity30 (5.2)10 (5.3)
Maternal smoking during pregnancy
 Nonsmoker at end of pregnancy469 (81.4)161 (85.2)
 Smoked at end of pregnancy76 (13.2)20 (10.6)
 Missing data31 (5.4)8 (4.2)
Maternal prepregnancy BMI (kg/m2)
 <25379 (65.8)97 (51.3)
 25–30109 (18.9)49 (25.9)
 >3040 (6.9)28 (14.8)
 Missing data48 (8.3)15 (7.9)
Child’s HLA§ genotype
 Protective (DQ6)168 (29.2)3 (1.6)
 Neutral (any other HLA not mentioned)111 (19.3)5 (2.6)
 Increased risk (≥1 copy of either DQ8 or DQ2)212 (36.8)93 (49.2)
 High risk (DQ8/DQ2 heterozygote)30 (5.2)71 (37.6)
 Missing data55 (9.5)17 (9.0)
Child’s non-HLA T1D GRS61.2 (45.7–76.3)63.2 (45.4–78.6)
 Missing data19 (3.5)12 (6.8)
Child’s 25(OH)D GRS3 (0–8)3 (0–8)
 Missing data20 (3.7)13 (7.4)
Cesarean section59 (10.2)36 (19.0)
  • Data are median (range) or n (%).

  • *Diagnosis date of the last case subject included: 3 February 2014.

  • †Median age at diagnosis of T1D case subjects was 5.7 years (range 0.7–12.7).

  • ‡Including those who quit smoking shortly before or during pregnancy.

  • §Groups defined as protective (carrying at least one copy of HLA DQA1*01:02-DQB1*06:02-DRB1*15:01 [DQ6-DR15]), increased risk (at least one copy of HLA DQA1*03-DQB1*03:02-DRB1*04 [DQ8-DR4] or DQA1*05:01-DQB1*02:01-DRB1*03:01 [DQ2-DR3] but not both haplotypes), high risk (HLA DQ2-DR3/DQ8-DR4), or neutral (any other genotype).

  • ‖Weighted score, calculated by multiplying the number of risk alleles in 51 non-HLA SNPs with their reported risk per allele.

  • ¶Includes unknown (n = 1), emergency (n = 55), and elective (n = 39) cesarean section.