Table 1 Baseline characteristics of the study population^a

Maternal age (y)

27.59 ± 4.02

27.03 ± 4.19

0.003

 ≤19

2

239

0.234

 20–34

476

18,974

 ≥35 (older pregnancy)

35

12,78

Height (cm)

156.23 ± 8.43

155.81 ± 7.32

0.201

Pre-pregnancy BMI

22.34 ± 5.86

22.02 ± 5.69

0.209

 <18.5

35

1,751

0.396

 18.5–24.9

408

16,137

 25–29.9

67

2,536

 ≥30

3

67

 Primary/under

15

892

0.288

 Middle/High school

171

6,785

 College/above

327

12,814

 0

373

15,524

0.258

 1

126

4,519

 ≥2

14

448

 0

456

18,607

0.385

 1

42

1,329

 ≥2

15

555

Previous preterm birth

0.907

 0

504

20,168

 1

9

320

 ≥2

0

3

 1

497

20,001

0.288

 ≥2

16

490

 No

509

20,344

0.869

 Yes

4

147

ALT (U/L)

24.75 ± 7.22

22.34 ± 6.49

<0.001