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Table 1 Maternal characteristics according to urinary iodine to creatinine ratio

From: Maternal iodine status in a multi-ethnic UK birth cohort: associations with autism spectrum disorder

   Iodine-to-creatinine ratio (cohort split into thirds)
  All participants lower third middle third higher third
I:Cr (μg/g), median (range) 83 59·5 (< 67) 83·1 (67 to 105) 121·9 (> 105)
N 6973 2325 2324 2324
I:Cr (μg/g), geometric mean (95% CI) 86·0 (85·0 to 87·2) 48·6 (48·1 to 49·2) 83·4 (82·9 to 83·8) 154·9 (154·9 to 159·3)
I:Cr (μg/g), median (IQR) 83·1 (59·3 to 121·0) 51·5 (42·8 to 59·5) 83·1 (74·4 to 93·3) 145·7 (121·0 to 185·9)
UIC (μg/L), geometric mean (95% CI) 70·8 (69·6 to 72·1) 45·9 (44·6 to 47·2) 69·9 (68·1 to 71·8) 110·6 (107·7 to 113·7)
UIC (μg/L), median (IQR) 76·3 (44·7 to 120·2) 52·1 (29·0 to 78·1) 77·4 (47·4 to 111·4) 117·8 (72·0 to 178·9)
Age (years), mean (SD) 27·2 (5·6) 26·5 (5·5) 27·3 (5·6) 27·9 (5·6)
BMI (kg/M2), mean (SD) 25·9 (5·5) 26·5 (5·7) 25·9 (5·4) 25·2 (5·1)
Socio-economic status
 Least deprived and most educated 1313 (21) 323 (16) 456 (22) 534 (26)
 Employed, not materially deprived 1299 (21) 353 (17) 458 (22) 488 (23)
 Employed, no access to money 966 (16) 338 (16) 313 (15) 315 (15)
 Receives benefits, not materially deprived 1671 (27) 666 (32) 527 (26) 478 (23)
 Most economically deprived 954 (15) 378 (19) 304 (15) 272 (13)
Ethnic background, n (%)
 White British & European 3020 (43) 847 (36) 1061 (46) 1112 (48)
 Pakistani 2951 (43) 1112 (48) 951 (41) 888 (38)
 Other (Black, Indian, mixed, other) 964 (14) 353 (15) 299 (13) 312 (14)
Parity
 0 3196 (46) 1015 (44) 1055 (46) 1126 (49)
 1 1896 (27) 617 (27) 640 (27) 639 (27)
 2 1075 (15) 376 (16) 363 (16) 336 (15)
 3+ 806 (12) 317 (14) 266 (11) 223 (10)
Health and lifestyle in pregnancy
 Gestational diabetes, n (%) 525 (8) 165 (7) 174 (8) 186 (8)
 Pre-pregnancy hypertension, n (%) 50 (1) 21 (1) 17 (1) 12 (1)
 Pregnancy-induced hypertension, n (%) 383 (5) 128 (5) 127 (5) 128 (6)
 Preeclampsia, n (%) 181 (3) 64 (3) 56 (2) 61 (3)
 Drank any alcohol, n (%) 1323 (19) 386 (17) 476 (20) 461 (20)
 Smoked, n (%) 1014 (15) 321 (14) 366 (16) 327 (14)
 Iodine-containing supplements, n (%) 1036 (15) 134 (6) 279 (12) 623 (27)
 Total fish intakea (g/d), mean (SD) 23·8 (29·3) 20·9 (28·3) 25·3 (30·8) 25·3 (28·4)
Eat 5 fruit/vegetables per daya, n (%)
 Always 441 (18) 128 (15) 164 (20) 149 (19)
 Sometimes 1782 (75) 628 (77) 595 (73) 559 (75)
 Never 154 (6) 59 (7) 52 (6) 43 (6)
  1. Abbreviations: 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. aData from women who were asked about diet in pregnancy (n = 2202)
  3. See definitions in Supplemental Table S3