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