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Table 1 Iodine exposures by characteristics of the study population (n = 78,318)

From: Insufficient maternal iodine intake is associated with subfecundity, reduced foetal growth, and adverse pregnancy outcomes in the Norwegian Mother, Father and Child Cohort Study

  Study population Iodine from food, median (IQR), μg/day Iodine supplement, GW 0–22, % UICa (n = 2795), median (IQR), μg/L
Study sample, n (%) 78,318 (100) 121 (89, 161) 37 69 (35, 116)
Maternal age at delivery, mean (SD), years 30.2 (4.5)    
 < 25 11 122 (85, 172) 35 68 (38, 108)
 25–34 72 121 (89, 160) 37 67 (35, 115)
 ≥ 35 17 122 (91, 160) 38 73 (37, 120)
Pre-pregnancy BMI, mean (SD), kg/m2 24.0 (4.3)    
 < 18.5 3.0 123 (89, 163) 40 64 (31, 128)
 18.5–24.9 66 122 (90, 161) 38 67 (34, 114)
 25–30 22 120 (87, 163) 36 69 (34, 118)
 > 30 9.5 118 (84, 161) 35 75 (44, 119)
Parity, %
 0 47 119 (87, 160) 42 68 (35, 116)
 1 36 122 (90, 161) 34 69 (34, 118)
 2 or more 17 127 (94, 168) 30 69 (40, 104)
Maternal education, %
 ≤ 12 years 31 122 (86, 168) 33 70 (39, 115)
 13–16 years 43 122 (89, 161) 38 68 (34, 114)
 > 16 years 27 120 (90, 155) 40 68 (34, 120)
Married/cohabitant, %
 Yes 96.7 121 (89, 161) 37 69 (35, 116)
 No 3.3 123 (88, 169) 37 69 (30, 103)
Smoking in pregnancy, %
 No 79 122 (89, 161) 38 70 (37, 119)
 Occasionally 16 120 (87, 162) 37 61 (31, 106)
 Daily 5.0 123 (87, 172) 32 62 (32, 95)
Chronic illness, %
 No 90 122 (90, 162) 37 68 (35, 116)
 Yes 10 116 (83, 158) 41 72 (34, 118)
Couples income
 Low 26 125 (90, 169) 35 72 (39, 115)
 Medium 41 122 (90, 163) 37 66 (34, 118)
 High 30 117 (87, 153) 40 69 (34, 114)
 Missing 2.7 129 (92, 175) 34 71 (47, 104)
Iodine supplement in pregnancy, %
 No 63 122 (89, 162) 0 59 (32, 100)
 Yes 37 121 (89, 161) 100 85 (45, 140)
 Reported use in GW 17–20 17 122 (89, 161) 100 99 (54, 154)
Vitamin D supplement (%) 77 123 (91, 162) 47 70 (36, 120)
Multivitamin/multimineral (%) 49 122 (90, 162) 66 76 (39, 129)
Folic acid before/early pregnancy (%) 73 121 (89, 159) 42 70 (36, 120)
Maternal energy intake, median (IQR), MJ 9.4 (7.9, 11.1)    
Iodine from food, median (IQR), μg/day 121 (89, 161)    
 < 75 16 61 (50, 68) 38 51 (27, 96)b
 75–149.9 54 112 (94, 129) 37 68 (34, 114)b
 ≥ 150 31 187 (166, 223) 37 78 (43, 129)b
  1. aUrinary iodine concentration (UIC) was measured in a subsample of n = 2795 pregnant women in mean gestational week 18.5 (SD 1.3). Iodine intake from food and use of iodine-containing supplements were comparable in this subgroup versus the whole study sample
  2. bRestricted to non-users of iodine-containing supplements