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Table 1 Maternal characteristics according to urinary iodine-to-creatinine ratio

From: Maternal iodine status, intrauterine growth, birth outcomes and congenital anomalies in a UK birth cohort

 

All participants, n = 6637

Iodine-to-creatinine ratio (sample split into thirds)

Lower third (< 67 μg/g), n = 2213

Middle third (67 to 105 μg/g), n = 2212

Higher third (> 105 μg/g), n = 2212

I:Cr (μg/g), geometric mean (99% CI)

86.0 (84.5 to 87.5)

48.5 (47.8 to 49.3)

83.4 (82.8 to 84.0)

157.2 (154.3 to 160.2)

I:Cr (μg/g), median (IQR)

83.1 (59.4 to 121.2)

51.4 (42.7 to 59.4)

83.2 (74.4 to 93.3)

146.1 (121.2 to 185.2)

UIC (μg/L), geometric mean (99% CI)

70.8 (69.1 to 72.5)

45.9 (44.2 to 47.8)

70.0 (67.6 to 72.6)

110.4 (106.4 to 114.5)

UIC (μg/L), median (IQR)

76.2 (44.6 to 120.2)

52.2 (29.1 to 78.0)

77.4 (47.3 to 112.5)

117.6 (71.8 to 178.8)

Age (years), mean (SD)

27.2 (5.6)

26.5 (5.5)

27.3 (5.6)

27.8 (5.6)

BMI (kg/m2), mean (SD)

25.8 (5.5)

26.5 (5.8)

25.9 (5.4)

25.1 (5.1)

Socioeconomic status†

 Least deprived and most educated

1241 (21)

307 (16)

429 (22)

505 (25)

 Employed, not materially deprived

1231 (21)

335 (17)

440 (22)

456 (23)

 Employed, no access to money

917 (16)

320 (16)

295 (15)

302 (15)

 Receives benefits, not materially deprived

1594 (27)

633 (32)

505 (26)

456 (23)

 Most economically deprived

920 (16)

360 (18)

293 (15)

267 (13)

Ethnic background, n (%)

 White British and European

2877 (44)

800 (36)

1016 (46)

1061 (48)

 Pakistani

2827 (43)

1064 (48)

914 (42)

849 (39)

 Others (Black, Indian, mixed, others)

901 (14)

337 (15)

271 (12)

293 (13)

Parity

 0

2931 (44)

933 (42)

966 (44)

1032 (47)

 1

1859 (28)

600 (27)

623 (28)

636 (29)

 2

1059 (16)

371 (17)

361 (16)

327 (15)

 3+

788 (12)

309 (14)

262 (12)

217 (10)

Health and lifestyle in pregnancy

 Gestational diabetes, n (%)

499 (8)

152 (7)

167 (8)

180 (8)

 Pre-pregnancy hypertension, n (%)

50 (0.8)

21 (1.0)

17 (0.8)

12 (0.5)

 Pregnancy-induced hypertension, n (%)

375 (6)

125 (6)

126 (6)

124 (6)

 Preeclampsia, n (%)

173 (3)

61 (3)

55 (2)

57 (3)

 Drank any alcohol, n (%)

958 (14)

299 (14)

335 (15)

324 (15)

 Smoked, n (%)

969 (15)

302 (14)

352 (16)

315 (14)

 Used any supplements, n (%)

1334 (20)

213 (10)

382 (17)

739 (33)

 Iodine-containing supplements, n (%)

988 (15)

123 (6)

264 (12)

601 (27)

 White fish intake* (g/day), mean (SD)

21.0 (27.0)

18.7 (26.3)

22.1 (28.2)

22.1 (26.1)

 Oily fish intake* (g/day), mean (SD)

1.4 (3.8)

1.0 (3.2)

1.5 (4.2)

1.7 (4.0)

 Total fish intake* (g/day), mean (SD)

23.8 (29.3)

20.8 (28.3)

25.1 (30.7)

25.4 (28.8)

Eat 5 fruits/vegetables per day*, n (%)

 Always

422 (19)

122 (16)

160 (21)

140 (19)

 Sometimes

1700 (75)

601 (77)

558 (72)

541 (75)

 Never

151 (7)

57 (7)

52 (7)

42 (6)

  1. BMI body mass index, CI confidence intervals, I:Cr urinary iodine-to-creatinine ratio, IQR interquartile range, SD standard deviation, UIC urinary iodine concentration
  2. *Data from women who were asked about diet in pregnancy (n = 2776)
  3. †Refer to supplement table S1 for details