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Table 1 Characteristics of participants according to baseline preconception thyrotropin levelsa

From: Evaluating the progression to abnormal thyrotropin in euthyroid preconception women: a population-based study

Characteristic

Overall (n = 186095)

Thyrotropin, median (IQR) mIU/L

Maternal preconception thyrotropin levels, mIU/L

0.37-1.00 (n = 32678)

1.01-2.00 (n = 78141)

2.01-3.00 (n = 49719)

3.01-4.00 (n - 19391)

4.01-4.87 (n = 6166)

P value

Thyrotropin, median (IQR), mIU/L

 

1.75 [1.19, 2.48]

0.77 [0.60, 0.90]

1.46 [1.24, 1.72]

2.40 [2.18, 2.64]

3.35 [3.16, 3.62]

4.30 [4.13, 4.53]

< 0.001b

Stratified for age (years)

       

< 0.001c

 20-24.9

78621(42.2)

1.72 [1.17, 2.45]

14340 (43.9)

33061 (42.3)

20682 (41.6)

8051 (41.5)

2487 (40.3)

 

 25-29.9

70921(38.1)

1.77 [1.20, 2.50]

12056 (36.9)

29575 (37.8)

19493 (39.2)

7433 (38.3)

2364 (38.3)

 

 30-34.9

23678 (12.7)

1.73 [1.19, 2.48]

4169 (12.8)

10014 (12.8)

6198 (12.5)

2488 (12.8)

809 (13.1)

 

 35-39.9

9216( 5.0)

1.75 [1.20, 2.48]

1545 ( 4.7)

3977 ( 5.1)

2380 ( 4.8)

980 ( 5.1)

334 ( 5.4)

 

 > 40

3659 ( 2.0)

1.82 [1.24, 2.61]

568 ( 1.7)

1514 ( 1.9)

966 ( 1.9)

439 ( 2.3)

172 ( 2.8)

 

Stratified for BMI (kg/m2)

       

< 0.001c

 < 18.5

22243 (12.0)

1.73 [1.16, 2.46]

4141 (12.7)

9299 (11.9)

5817 (11.7)

2257 (11.6)

729 (11.8)

 

 18.5-23.9

131433 (70.6)

1.74 [1.20, 2.47]

22868 (70.0)

55559 (71.1)

35366 (71.1)

13415 (69.2)

4225 (68.5)

 

 24.0-27.9

25184 (13.5)

1.76 [1.17, 2.51]

4529 (13.9)

10325 (13.2)

6580 (13.2)

2829 (14.6)

921 (14.9)

 

 > 28.0

6534 ( 3.5)

1.83 [1.24, 2.59]

1019 ( 3.1)

2658 ( 3.4)

1751 ( 3.5)

834 ( 4.3)

272 ( 4.4)

 

 Missing data

701 ( 0.4)

1.77 [1.20, 2.37]

121 ( 0.4)

300 ( 0.4)

205 ( 0.4)

56 ( 0.3)

19 ( 0.3)

 

Stratified for Parity

       

< 0.001c

 0

65662 (35.3)

1.75 [1.20, 2.45]

11369 (34.8)

27991 (35.8)

17826 (35.9)

6542 (33.7)

1934 (31.4)

 

 ≥ 1

108440 (58.3)

1.76 [1.20, 2.50]

18794 (57.5)

45159 (57.8)

29010 (58.3)

11654 (60.1)

3823 (62.0)

 

 Missing data

 11993 ( 6.4)

1.65 [1.10, 2.40]

2515 ( 7.7)

4991 ( 6.4)

2883 ( 5.8)

1195 ( 6.2)

409 ( 6.6)

 

Stratified for education

       

< 0.001c

 High school or above

126616 (68.0)

1.75 [1.19, 2.49]

22356 (68.4)

52553 (67.3)

33863 (68.1)

13525 (69.7)

4319 (70.0)

 

 Primary school or below

54989 (29.5)

1.74 [1.20, 2.46]

9515 (29.1)

23498 (30.1)

14794 (29.8)

5475 (28.2)

1707 (27.7)

 

 Missing data

4490 ( 2.4)

1.65 [1.18, 2.36]

807 ( 2.5)

2090 ( 2.7)

1062 ( 2.1)

391 ( 2.0)

140 ( 2.3)

 

Stratified for alcohol consumption

       

< 0.001c

 No

180000 (99.3)

1.74 [1.19, 2.47]

31704 (97.0)

75681 (96.9)

47997 (96.5)

18683 (96.3)

5935 (96.3)

 

 Yes

5201 ( 0.3)

1.83 [1.23, 2.58]

829 ( 2.5)

2102 ( 2.7)

1462 ( 2.9)

598 ( 3.1)

210 ( 3.4)

 

 Missing data

894 ( 0.4)

1.83 [1.21, 2.50]

145 ( 0.4)

358 ( 0.5)

260 ( 0.5)

110 ( 0.6)

 21 ( 0.3)

 

Stratified for active smoking

       

< 0.757c

 No

184778 (99.4)

1.90 [1.19, 2.48]

32473 (99.4)

77622 (99.3)

49394 (99.3)

19264(99.3)

6134 (99.5)

 

 Yes

536 (0.3)

1.93 [1.23, 2.51]

 81 ( 0.2)

233 ( 0.3)

152 ( 0.3)

55 ( 0.3)

15 ( 0.2)

 

 Missing data

672 ( 0.4)

1.87 [1.19, 2.36]

124 ( 0.4)

286 ( 0.4)

173 ( 0.3)

72 ( 0.4)

17 ( 0.3)

 

Stratified for secondhand smoke

       

< 0.001c

 No

165255 (88.8)

1.74 [1.19, 2.46]

29183 (89.3)

69701 (89.2)

43981 (88.5)

17006 (87.7)

5384 (87.3)

 

 Yes

20101 (10.8)

1.81 [1.22, 2.56]

3363 (10.3)

8126 (10.4)

5546 (11.2)

2303 (11.9)

763 (12.4)

 

 Missing data

739 ( 0.4)

1.75 [1.20, 2.45]

 132 ( 0.4)

314 ( 0.4)

192 ( 0.4)

82 ( 0.4)

19 ( 0.3)

 

Stratified for diabetes

       

< 0.001c

 No

182400 (98.0)

1.75 [1.20, 2.48]

31995 (97.9)

76607 (98.0)

48769 (98.1)

18992 (97.9)

6037 (97.9)

 

 Yes

2166 ( 1.2)

1.67 [1.11, 2.41]

456 ( 1.4)

 882 ( 1.1)

552 ( 1.1)

215 ( 1.1)

61 ( 1.0)

 

 Missing data

1529 ( 0.8)

1.80 [1.24, 2.62]

227 ( 0.7)

652 ( 0.8)

398 ( 0.8)

184 ( 0.9)

68 ( 1.1)

 

Stratified for hypertension

       

< 0.001c

 No

117793 (63.3)

1.72 [1.18, 2.45]

21129 (64.7)

49883 (63.8)

30877 (62.1)

12129 (62.5)

3775 (61.2)

 

 Yes

1817 ( 1.0)

1.86 [1.22, 2.63]

299 ( 0.9)

720 ( 0.9)

478 ( 1.0)

231 ( 1.2)

89 ( 1.4)

 

 Missing data

66485 (35.7)

1.78 [1.20, 2.50]

11250 (34.4)

27538 (35.2)

18364 (36.9)

7031 (36.3)

2302 (37.3)

 

Stratified for environmental iodine status

       

< 0.001c

 Adequate iodine

71800 (38.6)

1.73 [1.18, 2.46]

12708 (38.9)

30595 (39.2)

18990 (38.2)

7239 (37.3)

2268 (36.8)

 

 More than adequate iodine

94630 (50.9)

1.73 [1.18, 2.45]

17100 (52.3)

39594 (50.7)

25402 (51.1)

9572 (49.4)

2962 (48.0)

 

 Excess iodine

19665 ( 10.6)

1.88 [1.27, 2.65]

2870 ( 8.8)

7952 (10.2)

5327 (10.7)

2580 (13.3)

936 (15.2)

 
  1. Abbreviations: BMI body mass index (calculated as weight in kilograms divided by height in meters squared), IQR interquartile range
  2. aData presented as number (percentage) unless otherwise indicated
  3. bDifferences in the characteristics of participants with different thyrotropin levels were assessed using Kruskal–Wallis test for continuous variables
  4. cDifferences in categorical variables were evaluated using chi-square test
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Thyroid Research

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