Table 1 Basic characteristics of the study population

Thyroid function

0.082

  Euthyroid

34,943 (91.2)

1716 (90.1)

  Subclinical hyperthyoidism

378 (1.0)

27 (1.4)

  Hyperthyroidism

317 (0.8)

18 (0.9)

  Isolated hypothyroxinemia

826 (2.2)

52 (2.7)

  Isolated hyperthyroxinemia

431 (1.1)

21 (1.1)

  Overt hypothyroidism

37 (0.1)

4 (0.2)

  Subclinical hypothyroidism

753 (2.0)

30 (1.6)

TPOAb positive ^a

2465 (6.9)

147 (8.2)

0.001

TRAb positive ^a

683 (1.8)

29 (1.8)

0.121

TgAb positive ^a

2730 (8.1)

138 (8.1)

0.311

Maternal age, years (median, IQR)

29.0 (27.0–32.0)

29.0 (27.0–32.0)

< 0.001

Gestational week (median, IQR)

39.0 (38.0–40.0)

35.0 (34.0–36.0)

< 0.001

Local residents

29,478 (77.0)

1434 (75.3)

0.088

Nulliparous

32,524 (84.9)

1559 (81.8)

< 0.001

Assisted conception

654 (1.7)

61 (3.2)

< 0.001

Gestational diabetes

3161 (8.3)

196 (10.3)

0.002

Preeclampsia

1986 (5.2)

285 (15.0)

< 0.001

Male fetuses

19,674 (51.4)

1039 (54.5)

0.007