Table 5. Open in new tab Follow-up of...

	TSH < 0.1 mIU/L						TSH ≥ 0.1 mIU/L
Later hyperthyroid diagnosis	11	52.4	29.8-74.3	33	8.4	5.9-11.6	< 5	N/A	N/A	< 5	N/A	N/A
Later ATD treatment	10	47.6	25.7-70.2	17	4.3	2.5-6.8	< 5	N/A	N/A	< 5	N/A	N/A
Later thyroid surgery or radioiodine treatment	< 5	N/A	N/A	5	1.3	0.4-2.9	< 5	N/A	N/A	< 5	N/A	N/A
Later pregnancy	9	42.9	21.8-66.0	154	39.2	34.3-44.2	11	42.3	23.4-63.1	271	50.0	45.7-54.3
Hyperthyroidism in pregnancy or 2 y post partum^a	5	23.8	8.2-47.2	10	2.5	1.2-4.6	< 5	N/A	N/A	< 5	N/A	N/A
ATD in pregnancy or 2 y post partum^b	5	23.8	8.2-47.2	5	1.3	0.4-2.9	< 5	N/A	N/A	< 5	N/A	N/A

TSH < 0.1 mIU/L

TSH ≥ 0.1 mIU/L

TRAb > 1.0 IU/L

TRAb ≤ 1.0 IU/L

TRAb > 1.0 IU/L

TRAb ≤ 1.0 IU/L

n = 21

n = 393

n = 26

n = 542

RF (%)

95% CI

RF (%)

95% CI

RF (%)

95% CI

RF (%)

95% CI

Later hyperthyroid diagnosis

52.4

29.8-74.3

8.4

5.9-11.6

< 5

N/A

< 5

N/A

Later ATD treatment

47.6

25.7-70.2

4.3

2.5-6.8

< 5

N/A

< 5

N/A

Later thyroid surgery or radioiodine treatment

< 5

N/A

1.3

0.4-2.9

< 5

N/A

< 5

N/A

Later pregnancy

42.9

21.8-66.0

154

39.2

34.3-44.2

42.3

23.4-63.1

271

50.0

45.7-54.3

Hyperthyroidism in pregnancy or 2 y post partum^a

23.8

8.2-47.2

2.5

1.2-4.6

< 5

N/A

< 5

N/A

ATD in pregnancy or 2 y post partum^b

23.8

8.2-47.2

1.3

0.4-2.9

< 5

N/A

< 5

N/A

	TSH < 0.1 mIU/L						TSH ≥ 0.1 mIU/L
Later hyperthyroid diagnosis	11	52.4	29.8-74.3	33	8.4	5.9-11.6	< 5	N/A	N/A	< 5	N/A	N/A
Later ATD treatment	10	47.6	25.7-70.2	17	4.3	2.5-6.8	< 5	N/A	N/A	< 5	N/A	N/A
Later thyroid surgery or radioiodine treatment	< 5	N/A	N/A	5	1.3	0.4-2.9	< 5	N/A	N/A	< 5	N/A	N/A
Later pregnancy	9	42.9	21.8-66.0	154	39.2	34.3-44.2	11	42.3	23.4-63.1	271	50.0	45.7-54.3
Hyperthyroidism in pregnancy or 2 y post partum^a	5	23.8	8.2-47.2	10	2.5	1.2-4.6	< 5	N/A	N/A	< 5	N/A	N/A
ATD in pregnancy or 2 y post partum^b	5	23.8	8.2-47.2	5	1.3	0.4-2.9	< 5	N/A	N/A	< 5	N/A	N/A

Median

95% CI

Median

95% CI

No. of later ATD prescriptions^c

4-25

3-7

Table 5.

Open in new tab

Follow-up of all women with no prior thyroid diagnosis when stratified by levels of thyrotropin receptor antibodies and thyrotropin in early pregnancy

	TSH < 0.1 mIU/L						TSH ≥ 0.1 mIU/L
	TRAb > 1.0 IU/L			TRAb ≤ 1.0 IU/L			TRAb > 1.0 IU/L			TRAb ≤ 1.0 IU/L
	n = 21			n = 393			n = 26			n = 542
	n	RF (%)	95% CI	n	RF (%)	95% CI	n	RF (%)	95% CI	n	RF (%)	95% CI
Later hyperthyroid diagnosis	11	52.4	29.8-74.3	33	8.4	5.9-11.6	< 5	N/A	N/A	< 5	N/A	N/A
Later ATD treatment	10	47.6	25.7-70.2	17	4.3	2.5-6.8	< 5	N/A	N/A	< 5	N/A	N/A
Later thyroid surgery or radioiodine treatment	< 5	N/A	N/A	5	1.3	0.4-2.9	< 5	N/A	N/A	< 5	N/A	N/A
Later pregnancy	9	42.9	21.8-66.0	154	39.2	34.3-44.2	11	42.3	23.4-63.1	271	50.0	45.7-54.3
Hyperthyroidism in pregnancy or 2 y post partum^a	5	23.8	8.2-47.2	10	2.5	1.2-4.6	< 5	N/A	N/A	< 5	N/A	N/A
ATD in pregnancy or 2 y post partum^b	5	23.8	8.2-47.2	5	1.3	0.4-2.9	< 5	N/A	N/A	< 5	N/A	N/A

	TSH < 0.1 mIU/L						TSH ≥ 0.1 mIU/L
	TRAb > 1.0 IU/L			TRAb ≤ 1.0 IU/L			TRAb > 1.0 IU/L			TRAb ≤ 1.0 IU/L
	n = 21			n = 393			n = 26			n = 542
	n	RF (%)	95% CI	n	RF (%)	95% CI	n	RF (%)	95% CI	n	RF (%)	95% CI
Later hyperthyroid diagnosis	11	52.4	29.8-74.3	33	8.4	5.9-11.6	< 5	N/A	N/A	< 5	N/A	N/A
Later ATD treatment	10	47.6	25.7-70.2	17	4.3	2.5-6.8	< 5	N/A	N/A	< 5	N/A	N/A
Later thyroid surgery or radioiodine treatment	< 5	N/A	N/A	5	1.3	0.4-2.9	< 5	N/A	N/A	< 5	N/A	N/A
Later pregnancy	9	42.9	21.8-66.0	154	39.2	34.3-44.2	11	42.3	23.4-63.1	271	50.0	45.7-54.3
Hyperthyroidism in pregnancy or 2 y post partum^a	5	23.8	8.2-47.2	10	2.5	1.2-4.6	< 5	N/A	N/A	< 5	N/A	N/A
ATD in pregnancy or 2 y post partum^b	5	23.8	8.2-47.2	5	1.3	0.4-2.9	< 5	N/A	N/A	< 5	N/A	N/A

	Median	95% CI	Median	95% CI
No. of later ATD prescriptions^c	13	4-25	3	3-7

	Median	95% CI	Median	95% CI
No. of later ATD prescriptions^c	13	4-25	3	3-7

Abbreviations: β-hCG, β-human chorionic gonadotropin; ATD, antithyroid drugs; BMI, body mass index; fT4, free thyroxine; N/A, not available; RF, relative frequency; TRAb, thyrotropin receptor antibodies; TSH, thyrotropin.

^aHospital diagnosis of hyperthyroidism while pregnant or 2 years post partum.

^bPrescription of ATD in the period from 1 month before pregnancy until 2 years post partum.

^cNumber of prescriptions from the first prescription until December 31, 2020.

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