Table 2 Baseline clinical characteristics of pregnancies

Age, years

32.8 (30.2, 35.4)

31.4 (28.9, 34.5)

< 0.001

Multiparity, n (% of pregnancies)

62 (29.2%)

11,252 (31.6%)

0.466

History of abnormal pregnancy ^a, n (% of pregnancies)

41 (19.3%)

4165 (11.7%)

0.001

Pre-pregnancy BMI, kg/m²

22.0 (20.1, 24.4)

21.2 (19.5, 23.4)

< 0.001

Pre-pregnancy hypertension, n (% of pregnancies)

5 (2.4%)

222 (0.6%)

0.012

Pre-pregnancy DM, n (% of pregnancies)

1 (0.5%)

162 (0.5%)

0.382

History of PCOS, n (% of pregnancies)

5 (2.4%)

1449 (4.1%)

0.209

History of HDP, n (% of multiparity)

3 (4.8%)

437 (3.9%)

0.735

History of GDM, n (% of multiparity)

6 (9.7%)

883 (7.8%)

0.632

Family history of hypertension, n (% of pregnancies)

55 (25.9%)

6536 (18.3%)

0.004

Family history of DM, n (% of pregnancies)

32 (15.1%)

4092 (11.5%)

0.100

Conceived by IVF-ET, n (% of pregnancies)

11 (5.2%)

1635 (4.6%)

0.677

Thyroid function during early pregnancy

 TSH, µIU/mL

 FT4, pmol/L

 TPOAb positive, n (% of pregnancies)

0.87 (0.30, 1.70)

17.16 (15.62, 19.11)

53 (25.0%)

1.20 (0.67, 1.87)

15.48 (14.22, 16.93)

4190 (11.8%)

< 0.001

< 0.001

< 0.001