Table 1 Characteristics of study participants in PE cases and controls

N

130

341

Maternal age (years)

  < 25

14(10.77)

27(7.92)

0.052

 25 ~ 29

56(43.08)

179(52.49)

 30 ~ 34

38(29.23)

104(30.50)

  >  = 35

22(16.92)

31(9.09)

Education

 Low

46(35.38)

59(17.30)

 < 0.001

 Middle

53(40.77)

140(41.06)

 High

31(23.85)

142(41.64)

Gravidity

1.98 + -0.09

1.68 + -0.05

0.002

Parity

1.22 + -0.04

1.14 + -0.02

0.05

Folic acid intake

 None

33(25.38)

29(8.50)

 < 0.001

 Sometimes

29(22.31)

87(25.51)

 Nearly everyday

68(52.31)

225(65.98)

Threatened abortion

 No

102(78.46)

313(91.79)

 < 0.001

 Yes

28(21.54)

28(8.21)

Exercise

 None

42(32.31)

184(53.96)

 < 0.001

 1–2 times per week

34(26.15)

98(28.74)

 3–4 times per week

32(24.62)

38(11.14)

 5–7 times per week

22(16.92)

21(6.16)

Second hand smoking

 None

64(49.23)

235(68.91)

 < 0.001

 Less than 0.5 h a day

27(20.77)

79(23.17)

 0.5–1 h a day

27(20.77)

15(4.40)

 More than 1 h a day

12(9.23)

12(3.52)

Gestational age

37.20 + -0.28

39.19 + -0.13

 < 0.001

BMI at delivery

 Quantile 1

30(23.08)

89(26.25)

 < 0.001

 Quantile 2

20(15.38)

96(28.32)

 Quantile 3

30(23.08)

87(25.66)

 Quantile 4

50(38.46)

67(19.76)

Delivery mode

 Vaginal delivery

45(34.62)

289(84.75)

 < 0.001

 Caesarean section

85(65.38)

52(15.25)

Birth weight

2827.08 + -69.85

3303.19 + -30.26

 < 0.001

Postpartum Hemorrhage

 No

78(60.00)

279(81.82)

 < 0.001

 Yes

52(40.00)

62(18.18)

Maternal blood RTL

0.48(0.27–0.77)

0.30(0.24–0.36)

 < 0.001

Cord blood RTL

0.61(0.35–1.28)

0.35(0.29–0.42)

 < 0.001

Maternal blood mtDNA-CN

3.02(1.83–4.89)

2.00(1.15–3.31)

 < 0.001

Cord blood mtDNA-CN

1.69(0.91–3.60)

5.49(2.89–10.15)

 < 0.001