Table 2 Comparisons of maternal RTL and mtDNA-CN in subgroups of PE cases and controls

Overall

130

341

Maternal age (year)

0.1096

0.3575

0.8179

0.475

   < 25

14

0.56(0.42–0.77)

1.70(1.29–3.66)

27

0.30(0.25–0.36)

2.35(1.58–3.93)

   25 ~ 29

56

0.44(0.26–0.73)

3.17(1.52–5.02)

179

0.29(0.23–0.37)

1.86(1.02–3.09)

   30 ~ 34

38

0.41(0.26–0.82)

3.30(2.06–4.63)

104

0.31(0.25–0.35)

2.05(1.19–3.21)

    >  = 35

22

0.69(0.46–0.83)

2.94(2.09–5.49)

31

0.32(0.23–0.40)

2.23(1.03–4.42)

Education

0.1522

0.0972

0.928

0.9138

   Low

46

0.62(0.29–0.85)

2.26(1.38–4.77)

59

0.30(0.23–0.40)

2.17(1.05–3.52)

   Middle

53

0.45(0.25–0.74)

3.42(2.12–5.32)

140

0.30(0.24–0.37)

2.01(1.16–3.54)

   High

31

0.41(0.28–0.62)

3.03(1.92–4.16)

142

0.30(0.25–0.36)

1.98(1.15–3.25)

Previous pregnancy

0.1946

0.3067

0.0572

0.2386

   No

51

0.43(0.27–0.70)

2.96(1.66–4.30)

189

0.29(0.24–0.36)

2.04(1.27–3.31)

   Yes

79

0.55(0.28–0.82)

3.38(1.84–5.28)

152

0.31(0.24–0.38)

1.96(1.03–3.37)

Parity

0.1385

0.5436

0.0029

0.555

   Primiparous

102

0.45(0.27–0.73)

3.02(1.72–4.73)

291

0.29(0.24–0.36)

2.00(1.16–3.45)

   Multiparous

28

0.59(0.31–0.87)

3.21(1.88–5.54)

50

0.34(0.30–0.39)

2.01(1.04–3.05)

Folic acid intake

0.0281

0.6406

0.0369

0.5704

   No

33

0.67(0.39–0.88)

3.51(1.72–4.51)

29

0.26(0.22–0.32)

2.38(1.10–4.62)

   Yes

97

0.45(0.27–0.73)

2.94(1.83–5.02)

312

0.30(0.25–0.37)

1.99(1.15–3.25)

Threatened abortion

0.9862

0.1643

0.3249

0.6863

   No

102

0.48(0.27–0.82)

2.90(1.84–4.51)

313

0.30(0.24–0.36)

1.99(1.15–3.52)

   Yes

28

0.47(0.29–0.73)

4.01(1.64–6.11)

28

0.30(0.26–0.37)

2.12(1.12–2.96)

Exercise

 < 0.001

0.5665

0.0309

 < 0.001

   None or seldom

76

0.35(0.24–0.49)

3.01(1.92–5.04)

282

0.30(0.24–0.36)

2.18(1.31–3.57)

   Often

54

0.76(0.51–0.97)

3.04(1.57–4.67)

59

0.32(0.23–0.48)

1.03(0.95–2.12)

Second hand smoking

0.0761

0.8427

0.8967

0.0393

   None

64

0.45(0.28–0.76)

2.84(1.61–4.72)

235

0.30(0.24–0.36)

1.96(1.05–3.37)

   Less than 0.5 h a day

27

0.37(0.22–0.70)

3.17(1.85–6.22)

79

0.29(0.24–0.36)

1.84(1.01–2.86)

   0.5–1 h a day

27

0.60(0.34–0.86)

2.57(1.96–4.87)

15

0.33(0.22–0.43)

2.67(2.16–5.57)

   More than 1 h a day

12

0.71(0.33–0.81)

3.64(1.29–5.77)

12

0.28(0.22–0.38)

2.38(1.84–3.41)

Preterm delivery

0.9717

0.3489

0.5142

0.3924

   No

86

0.47(0.28–0.73)

2.75(1.76–4.74)

313

0.30(0.24–0.37)

1.98(1.12–3.22)

   Yes

44

0.49(0.27–0.81)

3.67(1.92–5.04)

28

0.29(0.24–0.36)

2.67(1.29–3.69)

BMI at delivery

0.2521

0.4288

0.2482

0.8637

   Quantile 1

30

0.70(0.26–0.91)

3.78(1.86–4.88)

89

0.29(0.23–0.34)

1.99(1.28–3.00)

   Quantile 2

20

0.52(0.28–0.77)

2.01(1.38–3.20)

96

0.30(0.24–0.37)

2.20(1.18–3.37)

   Quantile 3

30

0.46(0.37–0.79)

3.45(2.21–4.87)

87

0.30(0.24–0.37)

1.77(1.05–3.32)

   Quantile 4

50

0.43(0.26–0.66)

3.01(1.92–5.04)

67

0.31(0.25–0.37)

1.87(1.03–4.21)

Delivery mode

0.0105

0.2416

0.0308

0.1702

   Vaginal delivery

45

0.40(0.26–0.62)

3.02(1.66–4.16)

289

0.30(0.24–0.37)

1.96(1.05–3.37)

   Caesarean section

85

0.57(0.29–0.89)

3.01(1.88–5.31)

52

0.28(0.23–0.33)

2.25(1.42–3.25)

Low birth weight

0.311

0.7459

0.5765

0.1952

   No

93

0.45(0.27–0.73)

2.95(1.84–5.00)

318

0.30(0.24–0.37)

1.98(1.10–3.30)

   Yes

37

0.65(0.29–0.82)

3.51(1.68–4.89)

23

0.29(0.23–0.36)

2.69(1.38–3.52)

Postpartum hemorrhage

0.3484

0.459

0.4309

0.4442

   No

78

0.45(0.27–0.73)

3.17(1.89–4.88)

279

0.30(0.24–0.37)

2.03(1.15–3.58)

   Yes

52

0.55(0.28–0.81)

2.62(1.51–5.00)

62

0.29(0.24–0.35)

1.93(1.07–2.86)